Troubleshooting Always On VPN Error Code 864

When configuring an Always On VPN connection, the administrator may encounter a scenario in which a VPN connection fails using either Internet Key Exchange version 2 (IKEv2) or Secure Socket Tunneling Protocol (SSTP). On the Windows 10 client the error message states the following.

“Can’t connect to [connection name]. The remote access connection completed, but authentication failed because a certificate that validates the server certificate was not found in the Trusted Root Certification Authorities certificate store.”

Troubleshooting Always On VPN Error Code 864

In addition, the Application event log records an error message with Event ID 20227 from the RasClient source. The error message states the following.

“The user [username] dialed a connection name [connection name] which has failed. The error code returned on failure is 864.”

Troubleshooting Always On VPN Error Code 864

NPS Server Certificate

Error code 864 is commonly caused by a missing or invalid server certificate on the Network Policy Server (NPS) performing authentication for VPN clients. The NPS server must have a certificate installed in its local computer certificate store from a trusted certification authority (CA) that includes the following.

Subject Name

The subject name must match the hostname defined in the EAP configuration for VPN clients. This may be the NPS server’s hostname but could also be an alias when NPS load balancing is configured.

Troubleshooting Always On VPN Error Code 864

Enhanced Key Usage

The NPS server certificate must include the Server Authentication Enhanced Key Usage (EKU).

Troubleshooting Always On VPN Error Code 864

NPS Policy Configuration

The NPS server certificate must also be selected in the network policy used for VPN client authentication. To confirm correct certificate configuration, open the properties for the Always On VPN network policy and follow the steps below.

1. Select the Constraints tab.
2. Highlight Authentication Methods.
3. Highlight Microsoft: Protected EAP (PEAP) in the EAP Types field.
4. Click Edit.
5. Select the NPS server certificate from the Certificate issued to drop-down list.

Troubleshooting Always On VPN Error Code 864

Ensure the NPS server certificate is also used for client certificate authentication by performing the following steps.

1. Highlight Smart Card or other certificate.
2. Click Edit.
3. Select the NPS server certificate from the Certificate issued to drop-down list.
4. Click Ok.

Troubleshooting Always On VPN Error Code 864

Additional Information

Windows 10 Always On VPN Network Policy Server (NPS) Load Balancing

Always On VPN IKEv2 Policy Mismatch Error

Always On VPN IKEv2 Policy Mismatch ErrorThe Internet Key Exchange version 2 (IKEv2) VPN protocol is the protocol of choice for Windows 10 Always On VPN deployments where the highest levels of security and assurance are required. However, as I’ve written about in the past, often the default IKEv2 security settings are less than desirable. Before using IKEv2 VPN in a production environment the administrator will need to update these security settings accordingly.

Connection Failure

When configuring Windows Server Routing and Remote Access Service (RRAS) or a third-party VPN appliance to support IKEv2 using custom security policies, the administrator may encounter a scenario in which a connection cannot be established due to a policy mismatch error. When the connection attempt fails, an error will be recorded in the Windows Application event log from the RasClient source with Event ID 20227. The error message states the following:

“The user [username] dialed a connection named [connection name] which has failed. The error code returned on failure is 13868.”

Always On VPN IKEv2 Policy Mismatch Error

Error Code 13868

Error code 13868 translates to ERROR_IPSEC_IKE_POLICY_MATCH. Essentially this error indicates that the IKEv2 security policy on the client did not match the configuration on the server.

Server Configuration

To view the current IKEv2 IPsec policy configuration, open an elevated PowerShell command window and run the following command.

Get-VpnServerIPsecConfiguration

Always On VPN IKEv2 Policy Mismatch Error

Client Configuration

To ensure interoperability, the VPN client must be configured to use the same IKEv2 security policy as defined on the sever. To view a VPN client’s currently configured IKEv2 security policy, open an elevated PowerShell command window and run the following command.

Get-VpnConnection -Name [connection name] | Select-Object -ExpandProperty IPsecCustomPolicy

Always On VPN IKEv2 Policy Mismatch Error

Note: If this PowerShell command returns no output, the VPN connection is not using a custom IKEv2 IPsec security policy.

Updating Settings

Guidance for configuring IKEv2 security policies on Windows Server RRAS and Windows 10 can be found here.

Summary

IKEv2 policy mismatch errors can be resolved easily by ensuring both the VPN server and client are configured to use the same IPsec security policies. Use the PowerShell commands in the above referenced above to validate settings and make changes when necessary.

Additional Information

Windows 10 Always On VPN IKEv2 Security Configuration

Windows 10 Always On VPN IKEv2 Features and Limitations

Show-VpnConnectionIPsecConfiguration PowerShell script on Github

Set-IKEv2SecurityBaseline PowerShell script on Github

Error Importing Windows Server RRAS Configuration

Error Importing Windows Server RRAS Configuration Windows Server and the Routing and Remote Access Service (RRAS) is a popular choice for Windows 10 Always On VPN deployments. It is easy to implement and support, offers flexible scalability, and is cost-effective. In addition, it provides support for a TLS-based VPN protocol which is required for many deployments.

Configuration Backup

When deploying RRAS to support Always On VPN, it’s an excellent idea to export the configuration once all settings have been finalized. Often this is done by opening an elevated command window and running netsh.exe ras dump and piping the output to a text file, as shown here.

netsh.exe ras dump > rasconfig.txt

Import Error

Importing a saved configuration is accomplished by opening an elevated command window and running netsh.exe exec [filename], as shown here.

netsh.exe exec rasconfig.txt

Oddly, this doesn’t work by default. The import will fail and return the following error message.

“The following command was not found: ■.”

Error Importing Windows Server RRAS Configuration

Root Cause

Importing the RRAS configuration fails because the default configuration output is saved in Unicode format. Inexplicably this encoding is not recognized by netsh.exe when importing the configuration.

Workaround

Follow the steps below to save the configuration file in a format that can be imported using netsh.exe.

1. Open the exported configuration file using notepad.exe.
2. From the Menu bar choose File > Save As.
3. From the Encoding drop-down list choose ANSI.
4. Click Save.

Error Importing Windows Server RRAS Configuration

Once complete, import the file using netsh.exe exec [filename]. Restart the RemoteAccess service to apply the changes.

PowerShell

Administrators can use PowerShell to export the RRAS configuration and ensure the correct encoding format is used by default. To do this, open an elevated PowerShell window and run the following command.

Invoke-Command -ScriptBlock {netsh ras dump} | Out-File [filename] -Encoding ASCII

Additional Information

Windows 10 Always On VPN and Windows Server Routing and Remote Access Service (RRAS)

Windows 10 Always On VPN Protocol Recommendations for Windows Server Routing and Remote Access Service (RRAS)

Always On VPN RasMan Errors in Windows 10 1903

Always On VPN RasMan Errors in Windows 10 1903After deploying or upgrading to Windows 10 1903, administrators may find that Windows 10 Always On VPN connections fail to establish successfully. Always On VPN connections continue to work for Windows 10 1809 and earlier clients, however.

Important Note: The issue described in this article has been addressed in KB4505903 (build 18362.267) released July 26, 2019.

RasMan Event Log Errors

When this occurs, the application event log contains an error with Event ID 1000 that includes the following information.

“Faulting application name: svchost.exe_RasMan…”, “Faulting module name: rasmans.dll”, and “Exception code: 0xc0000005”

Always On VPN RasMan Errors in Windows 10 1903 Administrators may find that Windows 10 Always On VPN connections fail after deploying or upgrading to Windows 10 1903. Always On VPN connections continue to work for Windows 10 1809 and earlier clients. RasMan Event Log Errors When this occurs, the application event log contains an error with Event ID 1000 that includes the following information. “Faulting application name: svchost.exe_RasMan…”, “Faulting module name: rasmans.dll”, and “Exception code: 0xc0000005” Root Cause RasMan failures can occur in Windows 10 1903 clients when telemetry is disabled via group policy or the registry. Microsoft has identified the issue and is currently working on a fix. Workaround As a temporary workaround to restore Always On VPN connectivity, enable telemetry on Windows 10 1903 using Active Directory or local group policy, the local registry, or PowerShell. Group Policy Create a new GPO or edit an existing one by opening the group policy management console (gpmc.msc) and performing the following steps. 1. Expand Computer Configuration > Administrative Templates > Windows Components > Data Collection and Preview Builds 2. Double-Click Allow Telemetry. 3. Select Enabled. 4. Choose 1-Basic, 2-Enhanced, or 3-Full (do not select 0-Security). 5. Click Ok. Registry Telemetry can also be enabled locally by opening the registry editor (regedit.exe) and modifying the following registry setting. HKLM\SOFTWARE\Policies\Microsoft\Windows\DataCollection\AllowTelemetry DWORD = 1 Note: The AllowTelemetry value can be removed entirely, if desired. PowerShell PowerShell can also be used modify or remove the AllowTelemetry value on Windows 10 1903 clients. Run the following PowerShell command to update the AllowTelemetry setting. New-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Microsoft\Windows\DataCollection\' -Name AllowTelemetry -PropertyType DWORD -Value 1 -Force Optionally, run the following PowerShell command to remove the AllowTelemetry setting entirely. Remove-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Microsoft\Windows\DataCollection\' -Name AllowTelemetry Restart Required Once these changes have been made, restart the client and test the Always On VPN connection. Additional Information asdf

Root Cause

RasMan failures can occur in Windows 10 1903 clients when telemetry is disabled via group policy or the registry. Microsoft has identified the issue and is currently working on a fix.

Workaround

As a temporary workaround to restore Always On VPN connectivity, enable telemetry on Windows 10 1903 using Active Directory or local group policy, the local registry, or PowerShell.

Group Policy

Create a new GPO or edit an existing one by opening the group policy management console (gpmc.msc) and performing the following steps.

1. Expand Computer Configuration > Administrative Templates > Windows Components > Data Collection and Preview Builds
2. Double-click Allow Telemetry.
3. Select Enabled.
4. Choose 1-Basic, 2-Enhanced, or 3-Full (do not select 0-Security).
5. Click Ok.

Always On VPN RasMan Errors in Windows 10 1903 Administrators may find that Windows 10 Always On VPN connections fail after deploying or upgrading to Windows 10 1903. Always On VPN connections continue to work for Windows 10 1809 and earlier clients. RasMan Event Log Errors When this occurs, the application event log contains an error with Event ID 1000 that includes the following information. “Faulting application name: svchost.exe_RasMan…”, “Faulting module name: rasmans.dll”, and “Exception code: 0xc0000005” Root Cause RasMan failures can occur in Windows 10 1903 clients when telemetry is disabled via group policy or the registry. Microsoft has identified the issue and is currently working on a fix. Workaround As a temporary workaround to restore Always On VPN connectivity, enable telemetry on Windows 10 1903 using Active Directory or local group policy, the local registry, or PowerShell. Group Policy Create a new GPO or edit an existing one by opening the group policy management console (gpmc.msc) and performing the following steps. 1. Expand Computer Configuration > Administrative Templates > Windows Components > Data Collection and Preview Builds 2. Double-Click Allow Telemetry. 3. Select Enabled. 4. Choose 1-Basic, 2-Enhanced, or 3-Full (do not select 0-Security). 5. Click Ok. Registry Telemetry can also be enabled locally by opening the registry editor (regedit.exe) and modifying the following registry setting. HKLM\SOFTWARE\Policies\Microsoft\Windows\DataCollection\AllowTelemetry DWORD = 1 Note: The AllowTelemetry value can be removed entirely, if desired. PowerShell PowerShell can also be used modify or remove the AllowTelemetry value on Windows 10 1903 clients. Run the following PowerShell command to update the AllowTelemetry setting. New-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Microsoft\Windows\DataCollection\' -Name AllowTelemetry -PropertyType DWORD -Value 1 -Force Optionally, run the following PowerShell command to remove the AllowTelemetry setting entirely. Remove-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Microsoft\Windows\DataCollection\' -Name AllowTelemetry Restart Required Once these changes have been made, restart the client and test the Always On VPN connection. Additional Information asdf

Registry

Telemetry can also be enabled locally by opening the registry editor (regedit.exe) and modifying the following registry setting.

HKLM\SOFTWARE\Policies\Microsoft\Windows\DataCollection\AllowTelemetry DWORD = 1

Always On VPN RasMan Errors in Windows 10 1903 Administrators may find that Windows 10 Always On VPN connections fail after deploying or upgrading to Windows 10 1903. Always On VPN connections continue to work for Windows 10 1809 and earlier clients. RasMan Event Log Errors When this occurs, the application event log contains an error with Event ID 1000 that includes the following information. “Faulting application name: svchost.exe_RasMan…”, “Faulting module name: rasmans.dll”, and “Exception code: 0xc0000005” Root Cause RasMan failures can occur in Windows 10 1903 clients when telemetry is disabled via group policy or the registry. Microsoft has identified the issue and is currently working on a fix. Workaround As a temporary workaround to restore Always On VPN connectivity, enable telemetry on Windows 10 1903 using Active Directory or local group policy, the local registry, or PowerShell. Group Policy Create a new GPO or edit an existing one by opening the group policy management console (gpmc.msc) and performing the following steps. 1. Expand Computer Configuration > Administrative Templates > Windows Components > Data Collection and Preview Builds 2. Double-Click Allow Telemetry. 3. Select Enabled. 4. Choose 1-Basic, 2-Enhanced, or 3-Full (do not select 0-Security). 5. Click Ok. Registry Telemetry can also be enabled locally by opening the registry editor (regedit.exe) and modifying the following registry setting. HKLM\SOFTWARE\Policies\Microsoft\Windows\DataCollection\AllowTelemetry DWORD = 1 Note: The AllowTelemetry value can be removed entirely, if desired. PowerShell PowerShell can also be used modify or remove the AllowTelemetry value on Windows 10 1903 clients. Run the following PowerShell command to update the AllowTelemetry setting. New-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Microsoft\Windows\DataCollection\' -Name AllowTelemetry -PropertyType DWORD -Value 1 -Force Optionally, run the following PowerShell command to remove the AllowTelemetry setting entirely. Remove-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Microsoft\Windows\DataCollection\' -Name AllowTelemetry Restart Required Once these changes have been made, restart the client and test the Always On VPN connection. Additional Information asdf

Note: The AllowTelemetry value can be removed entirely, if desired.

PowerShell

PowerShell can also be used modify or remove the AllowTelemetry value on Windows 10 1903 clients. Run the following PowerShell command to update the AllowTelemetry setting.

New-ItemProperty -Path ‘HKLM:\SOFTWARE\Policies\Microsoft\Windows\DataCollection\’ -Name AllowTelemetry -PropertyType DWORD -Value 1 -Force

Optionally, run the following PowerShell command to remove the AllowTelemetry setting entirely.

Remove-ItemProperty -Path ‘HKLM:\SOFTWARE\Policies\Microsoft\Windows\DataCollection\’ -Name AllowTelemetry

Service Restart Required

Once these changes have been made, restart the Remote Access Connection Manager service (RasMan) using the Services mnagement console (services.msc) or by running the following PowerShell command.

Restart-Service RasMan -PassThru

Optionally, the client can be rebooted to apply these changes.

Additional Information

Windows 10 1903 Known Issues

 

Always On VPN and Azure MFA ESTS Token Error

Always On VPN and Azure MFA ESTS Token ErrorConfiguring Multifactor Authentication (MFA) is an excellent way to ensure the highest level of assurance for Always On VPN users. Azure MFA is widely deployed and commonly integrated with Windows Server Network Policy Server (NPS) using the NPS Extension for Azure MFA. Azure MFA has a unique advantage over many other MFA providers in that it supports MFA when using Protected Extensible Authentication Protocol (PEAP). This makes Azure MFA the solution of choice for integrating with Windows 10 Always On VPN deployments using client certificate authentication, a recommended security configuration best practice.

NPS Configuration

Installing and configuring the NPS extension for Azure MFA is straightforward. Configuration guidance from Microsoft can be found here.

Connection Issues

After installing the NPS extension for Azure MFA, administrators may find that Always On VPN connections fail and the user is never challenged for authentication. The connection eventually times out and returns the following error message.

“A connection to the remote computer could not be established, so the port used for this connection was closed.”

Always On VPN and Azure MFA ESTS Token Error

In addition, the Application event log on the Windows 10 client contains an Event ID 20221 from the RasClient source that includes the following error message.

“The user [username] dialed a connection named [connection] which has failed. The error code returned on failure is 0.”

Always On VPN and Azure MFA ESTS Token Error

NPS Event Log

Reviewing the event logs on the NPS server reveals more information. The Security event log contains an Event ID 6274 from the Microsoft Windows security auditing source that includes the following error message.

“Network Policy Server discarded the request for a user. Contact the Network Policy Administrator for more information.”

Always On VPN and Azure MFA ESTS Token Error

ESTS Token Error

Digging deeper in the operational event log on the NPS server, the AuthZAdminCh log (Applications and Services Logs > Microsoft > AzureMfa > AuthZ) contains an Event ID 3 from the AuthZ source indicating an ESTS_TOKEN_ERROR message.

Always On VPN and Azure MFA ESTS Token Error

Troubleshooting ESTS Token Error

Follow the steps below to troubleshoot the ESTS_TOKEN_ERROR.

Prerequisites

Ensure that all prerequisites are met. Validate the user is being synced to Azure Active Directory and that it is properly licensed for Azure MFA.

Certificates

As part of the NPS extension configuration, a certificate is created on the NPS server that is uploaded to Azure Active Directory. To validate the certificate was created and uploaded correctly, follow the troubleshooting guidance found here.

Enterprise Applications

The Azure Multi-Factor Auth Client and the Azure Multi-Factor Auth Connector enterprise applications must be enabled to support the NPS extension for Azure MFA. To confirm they are enabled, open an elevated PowerShell command window on the server where the Azure AD Connector is installed and run the following PowerShell commands.

Import-Module MSOnline
Connect-MsolService

Get-MsolServicePrincipal -AppPrincipalId “981f26a1-7f43-403b-a875-f8b09b8cd720” | Select-Object DisplayName, AccountEnabled

Get-MsolServicePrincipal -AppPrincipalId “1f5530b3-261a-47a9-b357-ded261e17918” | Select-Object DisplayName, AccountEnabled

Always On VPN and Azure MFA ESTS Token Error

If either or both enterprise applications are not enabled, enable them using the following PowerShell commands.

Set-MsolServicePrincipal -AppPrincipalId “981f26a1-7f43-403b-a875-f8b09b8cd720” -AccountEnabled $True

Set-MsolServicePrincipal -AppPrincipalId “1f5530b3-261a-47a9-b357-ded261e17918” -AccountEnabled $True

Once complete, restart the IAS service on the NPS server using the following PowerShell command.

Restart-Service IAS -PassThru

Additional Information

Windows 10 Always On VPN Network Policy Server (NPS) Load Balancing Strategies

Deploy Windows 10 Always On VPN with Microsoft Intune

Windows 10 Always On VPN Hands-On Training Classes Now Available

Troubleshooting Always On VPN Error Code 809

When testing an Always On VPN connection, the administrator may encounter a scenario where the VPN client fails to connect to the VPN server. On the Windows 10 client the error message states the following.

“Can’t connect to [connection name]. The network connection between your computer and the VPN server could not be established because the remote server is not responding. This could be because one of the network devices (e.g. firewalls, NAT, routers, etc.) between your computer and the remote server is not configured to allow VPN connections. Please contact your Administrator or your service provider to determine which device may be causing the problem.”

Always On VPN and IKEv2 Fragmentation

In addition, the Application event log records an error message with Event ID 20227 from the RasClient source. The error message states the following.

“The User [username] dialed a connection named [connection name] with has failed. The error code returned on failure is 809.”

Troubleshooting Always On VPN Error Code 809

Connection Timeout

The error code 809 indicates a VPN timeout, meaning the VPN server failed to respond. Often this is related directly to network connectivity, but sometimes other factors can come in to play.

Troubleshooting VPN Error Code 809

When troubleshooting VPN error code 809 the following items should be carefully checked.

  • Name Resolution – Ensure the VPN server’s public hostname resolves to the correct IP address.
  • Firewall Configuration – Confirm the edge firewall is configured properly. Inbound TCP port 443 is required for the Secure Socket Tunneling Protocol (SSTP) and inbound UDP ports 500 and 4500 are required for the Internet Key Exchange version 2 (IKEv2) protocol. Make sure that any NAT rules are forwarding traffic to the correct server.
  • Load Balancer Configuration – If VPN servers are located behind a load balancer, make certain that virtual IP address and ports are configured correctly and that health checks are passing. For IKEv2 specifically, it is crucial that UDP ports 500 and 4500 be delivered to the same backend server. This commonly requires custom configuration. For example, on the KEMP LoadMaster the administrator will configure “port following”. On the F5 BIG-IP a  custom “persistence profile” must be configured. On the Citrix NetScaler a “persistency group” must be defined.

IKEv2 Fragmentation

VPN error code 809 can also be caused by IKE fragmentation when using the IKEv2 VPN protocol. During IKEv2 connection establishment, payload sizes may exceed the IP Maximum Transmission Unit (MTU) for the network path between the client and server. This causes the IP packets to be fragmented. However, it is not uncommon for intermediary devices (routers, NAT devices, or firewalls) to block IP fragments. When this occurs, a VPN connection cannot be established. However, looking at a network trace of the connection attempt, the administrator will see that the connection begins but subsequently fails.

Troubleshooting Always On VPN Error Code 809

Enable IKEv2 Fragmentation Support

The IKEv2 protocol includes support for fragmenting packets at the IKE layer. This eliminates the need for fragmenting packets at the IP layer. IKEv2 fragmentation must be configured on both the client and server.

Client

IKEv2 fragmentation was introduced in Windows 10 1803 and is enabled by default. No client-side configuration is required.

Server

IKEv2 is commonly supported on many firewall and VPN devices. Consult the vendor’s documentation for configuration guidance. For Windows Server Routing and Remote Access (RRAS) servers, IKEv2 fragmentation was introduced in Windows Server 1803 and is also supported in Windows Server 2019. It is enabled via a registry key. The following PowerShell command can be used to enable IKEv2 fragmentation on supported servers.

New-ItemProperty -Path “HKLM:\SYSTEM\CurrentControlSet\Services\RemoteAccess\Parameters\Ikev2\” -Name EnableServerFragmentation -PropertyType DWORD -Value 1 -Force

Validation

Once IKEv2 fragmentation is configured on the VPN server, a network capture will reveal the IKE_SA_INIT packet now includes the IKEV2_FRAGMENTATION_SUPPORTED notification message.

Always On VPN and IKEv2 Fragmentation

Additional Information

Windows 10 Always On VPN and IKEv2 Fragmentation

Windows 10 Always On VPN IKEv2 Security Configuration

Windows 10 Always On VPN Hands-On Training Classes

Always On VPN and IKEv2 Fragmentation

The IKEv2 protocol is a popular choice when designing an Always On VPN solution. When configured correctly it provides the best security compared to other protocols. The protocol is not without some unique challenges, however. IKEv2 is often blocked by firewalls, which can prevent connectivity. Another lesser know issue with IKEv2 is that of fragmentation. This can result in failed connectivity that can be difficult to troubleshoot.

IP Fragmentation

IKEv2 uses UDP for transport, and typically most packets are relatively small. The exception to this is when authentication takes place, especially when using client certificate authentication. The problem is further complicated by long certificate chains and by RSA keys, especially those that are greater than 2048 bit. If the payload exceeds 1500 bytes, the IP packet will have to be broken in to smaller fragments to be sent over the network. If an intermediary device in the path is configured to use a smaller Maximum Transmission Unit (MTU), that device may fragment the IP packets.

IP Fragmentation and Firewalls

Many routers and firewalls are configured to drop IP fragments by default. When this happens, IKEv2 communication may begin initially, but subsequently fail. This typically results in an error code 809 with a message stating the following.

“Can’t connect to [connection name]. The network connection between your computer and the VPN server could not be established because the remote server is not responding. This could be because one of the network devices (e.g. firewalls, NAT, routers, etc.) between your computer and the remote server is not configured to allow VPN connections. Please contact your Administrator or your service provider to determine which device may be causing the problem.”

Always On VPN and IKEv2 Fragmentation

Troubleshooting

When troubleshooting potential IKEv2 fragmentation-related connection failures, a network trace should be taken of the connection attempt on the client. Observe the packet sizes during the conversation, especially IKE_AUTH packets. Packet sizes exceeding the path MTU will have to be fragmented, as shown here.

Always On VPN and IKEv2 Fragmentation

Measuring Path MTU

Measuring the path MTU between the client and server can be helpful when troubleshooting fragmentation related issues. The mtupath.exe utility is an excellent and easy to use tool for this task. The tool can be downloaded here.

Always On VPN and IKEv2 Fragmentation

IKEv2 Fragmentation

To address the challenges with IP fragmentation and potential connectivity issues associated with network devices dropping fragmented packets, the IKEv2 protocol itself can be configured to perform fragmentation at the IKE layer. This eliminates the need for IP layer fragmentation, resulting in better reliability for IKEv2 VPN connections.

Both the server and the client must support IKEv2 fragmentation for this to occur. Many firewall and VPN vendors include support for IKEv2 fragmentation. Consult the vendor’s documentation for configuration guidance. For Windows Server Routing and Remote Access (RRAS) servers, the feature was first introduced in Windows Server 1803 and is supported in Windows Server 2019. Windows 10 clients support IKEv2 fragmentation beginning with Windows 10 1803.

Enabling IKEv2 Fragmentation

Windows 10 clients support IKEv2 fragmentation by default. However, it must be enabled on the server via the registry. The following PowerShell command will enable IKEv2 fragmentation support on Windows Server 1803 and later.

New-ItemProperty -Path “HKLM:\SYSTEM\CurrentControlSet\Services\RemoteAccess\Parameters\Ikev2\” -Name EnableServerFragmentation -PropertyType DWORD -Value 1 -Force

Validation Testing

Once IKEv2 fragmentation is configured on the VPN server, a network capture will reveal the IKE_SA_INIT packet now includes the IKEV2_FRAGMENTATION_SUPPORTED notification message.

Always On VPN and IKEv2 Fragmentation

Additional Information

Windows 10 Always On VPN IKEv2 Security Configuration

RFC 7383 – IKEv2 Message Fragmentation

IEA Software MTU Path Scan Utility

Windows 10 Always On VPN Hands-On Training Classes

Always On VPN Unable to Create Profile General Error

Always On VPN Unable to Create Profile General ErrorWhen configuring a Windows 10 Always On VPN profile connection using the Microsoft-provided MakeProfile.ps1 PowerShell script or my PowerShell Always On VPN deployment script, the creation of a new connection may fail and the administrator may encounter the following error message.

Unable to create [connection name] profile: A general error occurred that is not covered by a more specific error code.

Always On VPN Unable to Create Profile General Error

This error message is, of course, terribly ambiguous and provides no real actionable information for the administrator to resolve the problem with. This makes troubleshooting this error somewhat challenging.

Probable Cause

In my experience, this error message is almost always related to a syntax error in ProfileXML. For example, to generate the error message above, my XML file included the following error.

Always On VPN Unable to Create Profile General Error

In this example, the setting should be True or False. The setting “foo” is unrecognized and causes the ambiguous error message. It can also happen if mutually exclusive configuration settings are defined. For example, it can occur if the DisableClassBasedDefaultRoutes element is set to true when the RoutingPolicyType element is set to ForceTunneling.

Error Resolution

The only way to resolve this error is to ensure there are no configuration errors for any defined elements in ProfileXML. Review the file carefully for errors such as typos or elements that are out of place. Refer to the VPNv2 Configuration Service Provider (CSP) ProfileXML XSD for detailed syntax examples. In addition, I have some sample ProfileXML configuration files that can be used for reference on my GitHub page.

XML Format Validation

To ensure ProfileXML is properly formatted, it is recommended that an XML editor be used when generating or editing the configuration file. This will ensure that all defined elements are well-formed, and that all tags are properly closed. Use caution though, because some XML editors (including some popular online formatting tools) will insert XML version and encoding information at the beginning of the file. This information must be removed from ProfileXML prior to deployment.

Additional Information

Windows 10 VPNv2 Configuration Service Provider (CSP) Reference

Windows 10 VPNv2 Configuration Service Provider (CSP) ProfileXML XSD Native Profile Examples

Windows 10 Always On VPN PowerShell Scripts and Sample ProfileXML Configuration Files on GitHub

Free Online XML Formatter

Windows 10 Always On VPN Hands-On Training Classes for 2019

Always On VPN IKEv2 Connection Failure Error Code 800

Always On VPN administrators may encounter a scenario in which Windows 10 clients are unable to establish an IKEv2 VPN connection to a Windows Server Routing and Remote Access Service (RRAS) server or a third-party VPN device under the following conditions.

  1. The VPN connection is configured using ProfileXML.
  2. ProfileXML includes the <CryptographySuite> element.
  3. The VPN server is configured to use a custom IPsec policy.
  4. The VPN server supports only IKEv2.
  5. The <NativeProtocolType> in ProfileXML is set to Automatic.

When these specific conditions are met, the client will be unable to connect to the VPN server using IKEv2. The error message states:

The remote connection was not made because the attempted VPN tunnels failed. The VPN server might be unreachable. If this connection is attempting to use an L2TP/IPsec tunnel, the security parameters required for IPsec negotiation might not be configured properly.

Always On VPN IKEv2 VPN Connection Failure Error Code 800

In addition, the event log will include an error message from the RasClient source with event ID 20227 that includes the following error message.

The user [username] dialed a connection named [connection name] which has failed. The error code returned on failure is 800.

Always On VPN IKEv2 VPN Connection Failure Error Code 800

A manually configured VPN connection using IKEv2 will connect successfully under these same conditions, however.

IKEv2 Error Code 800

Error code 800 translates to ERROR_AUTOMATIC_VPN_FAILED, which is somewhat ambiguous. The error description is:

Unable to establish the VPN connection. The VPN server may be unreachable, or security parameters may not be configured properly for this connection.

Digging Deeper

A network trace of the IKEv2 VPN connection reveals the true source of the problem, which is a failure of the client and server to successfully negotiate an IKEv2 security association (SA). During the SA initiation process, the parameters offered by the client are unacceptable to the server, resulting in a NO_PROPOSAL_CHOSEN notification being returned by the server.

Always On VPN IKEv2 VPN Connection Failure Error Code 800

Custom Cryptography Settings Ignored

It appears that the Always On VPN connection ignores the custom cryptography settings defined in the CryptographySuite element in ProfileXML. However, this only occurs when the NativeProtocolType is set to Automatic. Presumably, this is a bug. 🙂

Workaround

As a workaround, set the NativeProtocolType to IKEv2. When NativeProtocolType is set to IKEv2, the VPN connection recognizes the IKEv2 parameters defined in the CryptographySuite element and the VPN connection will be established successfully.

Additional Information

Always On VPN IKEv2 Security Configuration

Always On VPN Certificate Requirements for IKEv2

Always On VPN IKEv2 Load Balancing with the KEMP LoadMaster Load Balancer

DirectAccess IP-HTTPS Not Working Properly in Windows Server 2019

After installing and configuring DirectAccess in Windows Server 2019 you may encounter an error message indicating that IP-HTTPS is not working properly. Looking at the Operations Status overview in the Dashboard of the Remote Access Management console shows that the IP-HTTPS interface is in error.

DirectAccess IP-HTTPS Not Working Properly in Windows Server 2019

IP-HTTPS Route Error

Viewing the detailed Operations Status shows the following error message.

Error: The IP-HTTPS route does not have published property enabled.

DirectAccess IP-HTTPS Not Working Properly in Windows Server 2019

Missing Route

Looking at the routing table on the DirectAccess server reveals that a route to the client IPv6 prefix is indeed missing.

DirectAccess IP-HTTPS Not Working Properly in Windows Server 2019

Resolution

To resolve this error message, add the client IPv6 route to the DirectAccess server’s routing table and publish it. This is accomplished by running the following PowerShell commands on the DirectAccess server.

$IPv6prefix = (Get-RemoteAccess).ClientIPv6Prefix
New-NetRoute -AddressFamily IPv6 -DestinationPrefix $IPv6prefix -InterfaceAlias “Microsoft IP-HTTPS Platform Interface” -Publish Yes

Next, restart the Remote Access Management service (RaMgmtSvc) using the following PowerShell command.

Restart-Service RaMgmtSvc -PassThru

DirectAccess IP-HTTPS Not Working Properly in Windows Server 2019

Once complete, refresh the management console and the IP-HTTPS error message should be resolved and the operations status should state that it is now working properly.

DirectAccess IP-HTTPS Not Working Properly in Windows Server 2019

 

Additional Information

SSL Certificate Conisderations for DirectAccess IP-HTTPS

DirectAccess Expire IP-HTTPS Certificate and Error 0x800b0101

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