Always On VPN Error -2146762495

DirectAccess Troubleshooting and the Windows 10 Network Connectivity Assistant

Always On VPN Administrators may encounter a scenario where Always On VPN connections suddenly stop working for all clients using the Secure Socket Tunneling Protocol (SSTP) VPN protocol. IKEv2 VPN connections continue to work, however.

Event Log

Reviewing the event log on a client machine reveals an error event ID 20227 from the RasClient source. 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 -2146762495.”

Error -2146762495?

Always On VPN administrators will be familiar with error codes such as 809, 691 and 812, 853, 858, and even 13801, 13806, and 13868. However, this error code seems to be formatted much differently. As it turns out, this message is in decimal format. Thankfully it’s pretty easy to convert it to something more meaningful, like hexadecimal. To do this, open the Windows calculator (calc.exe) and switch to programmer mode. Highlight DEC and enter -2146762495. The hexadecimal value will be displayed in the HEX field, as shown here.

Error 0x800B0101

After converting the error message from decimal to hex, use the Microsoft Error Lookup tool (err.exe) to translate the hex value of this error. As shown here, 0x800B0101 translates to CERT_E_EXPIRED.

Expired TLS Certificate

Once again, an expired certificate is to blame! In this case, the TLS certificate installed on the VPN server has expired and is no longer valid.

Resolution

The problem is simple enough to resolve, of course. Obtain a new TLS certificate from your certification authority (CA) of choice and update your VPN server configuration. You can find detailed guidance for updating the RRAS VPN server’s TLS certificate here. You will also find a video demonstration of the RRAS SSL/TLS certificate renewal process here.

Additional Information

Installing or Renewing an SSL/TLS Certificate on Windows Server RRAS for Always On VPN and SSTP

VIDEO: Installing or Renewing an SSL/TLS certificate on Windows Server RRAS for Always On VPN and SSTP

Microsoft Windows Always On VPN SSTP Security Configuration

Microsoft Windows Always On VPN SSL/TLS Certificate Requirements for SSTP

Microsoft Windows Always On VPN SSTP with Let’s Encrypt Certificates

Always On VPN and TLS 1.3

Secure Socket Tunneling Protocol (SSTP) is a Microsoft-proprietary VPN protocol with several advantages over Internet Key Exchange version 2 (IKEv2) for Always On VPN user tunnel connections. SSTP uses HTTP with Transport Layer Security (TLS) to encrypt communication between the Always On VPN client and the VPN gateway. SSTP is very firewall-friendly, with VPN connections operating on the commonly open TCP port 443, resulting in more consistent VPN availability. SSTP throughput is better compared to IKEv2 as well.

Learn more about TLS with Practical TLS, a comprehensive online video training course.

TLS and Windows Server

For versions of Windows Server before Windows Server 2022, the out-of-the-box security for TLS is not ideal. TLS is notoriously complex to configure, with myriad options for administrators to choose from. However, with the release of Windows Server 2022 and Windows 11, Microsoft has introduced support for the latest TLS specification, TLS 1.3, which eases much of this configuration pain.

TLS 1.3

TLS 1.3 provides significant advantages for Always On VPN SSTP user tunnel connections in security and performance.

Security

TLS 1.3 is greatly simplified and offers only five cipher suites, all considered secure by today’s standards. In addition, all TLS 1.3 ciphers support forward secrecy, ensuring the privacy of communication even in the event of a server private key compromise.

Performance

The TLS handshake in TLS 1.3 is streamlined and requires less back-and-forth (round trips) to establish a connection. TLS 1.3 speeds connection establishment for new Always On VPN user tunnel connections.

Caveat

Adding support for TLS 1.3 on the server-side is a compelling reason to consider upgrading existing Windows Server Routing and Remote Access Service (RRAS) servers to Windows Server 2022. However, TLS 1.3 support for SSTP also requires Windows 11 on the client-side. TLS 1.3 is not currently supported in Windows 10.

Summary

Realizing the performance benefits provided by TLS 1.3 will likely only occur in large environments supporting many thousands of concurrent connections per server. However, the security benefits apply to all deployments, regardless of size. Administrators should consider upgrading to Windows Server 2022 before proceeding with Windows 11 adoption.

Additional Information

Practical TLS: A Deep Dive into SSL and TLS Online Video Training Course

Always On VPN SSTP Security Configuration

Always On VPN SSTP with Let’s Encrypt Certificates

Always On VPN TLS Certificate Requirements for SSTP

TLS Protocol Version Support in Windows

TLS Cipher Suites in Windows Server 2022

A Detailed Look at TLS 1.3

TLS Cipher Suite Reference

RFC8446 TLS 1.3

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