Windows Error 809 when using VPN

I’ve set up a VPN  Server on a Windows Server 2012r2 which I usually access from my iPhone or Macbook pro. Once the correct ports are forwarded it was pretty simple and always worked. I recently tried to connect from my Windows 7 machine and my Windows 10 machine both without success.

The Windows 7 error was:

809: The network connection between your computer and the VPN server could not be established because the remote server is not responding…

and the Windows 10 error was:

File Metadata optimization is already in progress.

For this test  my server was behind a NAT but the clients were not. Since neither the iOS or MacOS systems were behind a NAT, I felt that the network configuration of the server was not contributing to the error.  Nevertheless, I searched for  ‘errors’ ‘nat’ ‘vpn’ and I got a hit for at Client behind NAT devices.

I made the following registry change specified in the post for both the Windows 7 and Windows 10 client machines:

RegValue:       AssumeUDPEncapsulationContextOnSendRule
Type:               DWORD
Data Value:    2

Then rebooted each system and they both now connect to the VPN server.

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