Updated December 9, 2023: I’ve recently updated this PowerShell script to work more reliably in different configurations other than the Getting Started Wizard. If you’ve had trouble running this script in the past, download the latest version. It should work better! I’ve also published the script in the PowerShell gallery. You can install it by running “Install-Script Renew-DaSelfSignedCertificates”. Enjoy!
When DirectAccess is deployed using the Getting Started Wizard (GSW), sometimes referred to as the “simplified deployment” method, self-signed certificates are created during the installation and used for the IP-HTTPS IPv6 transition technology, the Network Location Server (NLS), and for RADIUS secret encryption. Administrators may also selectively choose to use self-signed certificates for IP-HTTPS, or when collocating the NLS on the DirectAccess server. The RADIUS encryption certificate is always self-signed.
Certificate Expiration
These self-signed certificates expire 5 years after they are created, which means many DirectAccess administrators who have used this deployment option will need to renew these certificates at some point in the future. Unfortunately, there’s no published guidance from Microsoft on how to accomplish this. However, the process is simple enough using PowerShell and the New-SelfSignedCertificate cmdlet.
PowerShell Script on GitHub
The PowerShell script to renew DirectAccess self-signed certificates has been published on GitHub. You can download Renew-DaSelfSignedCertificates.ps1 here.
Important Considerations
When the IP-HTTPS certificate is renewed using this script, DirectAccess clients outside will be immediately disconnected and will be unable to reconnect until they update group policy. This will require connecting to the internal network locally or remotely using another VPN solution. The NLS and RADIUS encryption certificates can be updated without impacting remote users.
In addition, internal clients that are not online when this change is made will be unable to access internal resources by name until they update group policy. If this happens, delete the Name Resolution Policy Table (NRPT) on the client using the following PowerShell command and reboot to restore connectivity.
Get-Item -Path “HKLM:\SOFTWARE\Policies\Microsoft\Windows NT\DNSClient\DnsPolicyConfig” | Remove-Item -Confirm:$false
Additional Information
PowerShell Recommended Reading for DirectAccess Administrators
Configuring Multifactor Authentication (MFA) is an excellent way to ensure the highest level of assurance for Always On VPN users. 
