How to install VPN with SSTP for RRAS on Windows Server?

Install IIS and RRAS:

In Server Manager, go to "Add Roles and Features" and check Remote Access and Web Server (IIS).
In the Features pane, select Remote Server Administration Tools and all submodules. Under Remote Access Role Services, select DirectAccess, VPN, and Routing.

Install WACS for Let's Encrypt:

Configure RRAS:

Open the "rrasmgmt.msc" console.
Right-click on the server name and select "Configure" → "Custom Configuration" → "VPN Access & Demand-dial connections".
Start the RRAS service.
Right-click the server and go to Properties.
In the IPv4 tab, select a static address pool and choose an appropriate IP range for VPN clients (e.g., 192.168.25.40, 192.168.25.80).

Configure IIS for SSTP:

Ensure that the "Default Web Site" in IIS has an HTTPS binding without Server Name Identification (SNI).

To remove any existing certificates for the VPN host, open an admin terminal and run:

$hostname = "vpn.company.com"
      Get-ChildItem -Path Cert:\LocalMachine\My | Where-Object {$_.Subject -match $hostname} | Remove-Item

Edit the "settings_default.json" file for 4096-bit key size and run:

C:\WACS\wacs.exe --ocsp-must-staple

Place the generated certificate in the Personal store and follow all additional installation steps.

In RRAS properties, under security settings, select the newly created certificate for SSTP.

Note: Let's Encrypt certificates expire every 3 months, but WACS automatically reschedules updates.

Set RRAS to start on machine boot:

Open "services.msc".
Find the "Remote Access Connection Manager" service, right-click, go to Properties, and set the Startup type to Automatic.

Disable default gateway on the remote network:

Open the Network and Sharing Center and go to Change adapter settings.
Right-click on the VPN connection, select "Properties," and switch to the Networking tab.
Select the "Internet Protocol Version 4 (TCP/IPv4)" list item, click "Properties," go to Advanced, and uncheck "Use default gateway on remote network."

Troubleshooting:

Ensure that the VPN user is allowed to dial-in by running "mmc.exe" and adding the Local Users and Groups snap-in. Go to the user account properties, select the Dial-in tab, and allow access under Network Access Permission.
If Network Policy Server (NPS) is enabled, configure it to allow VPN connections. In the NPS snap-in from "mmc.exe," go to Advanced Configuration → Network Policies and grant access to both policies relating to VPN connections (they are denied by default).
Make sure the host machine is discoverable by enabling network discovery and file and printer sharing in the Network and Sharing Center settings.

All good? AWESOME!

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