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Windows 10 vpn L2TP connection error : 789

Question

Monday, January 28, 2019 11:44 AM

I have setup a vpn connection for my client server and logged in couple of times. The connection is not stable and logs out automatically. And now I am unable to log in back to VPN: error 789: "The L2TP connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer". please help!!!

All replies (1)

Tuesday, January 29, 2019 2:50 AM âś…Answered

Hi,

Possible causes for this issue could be:

  • L2TP based VPN client (or VPN server) is behind NAT.

 create and configure the AssumeUDPEncapsulationContextOnSendRule registry value.

Please refer to the link below:

https://support.microsoft.com/en-us/help/926179/how-to-configure-an-l2tp-ipsec-server-behind-a-nat-t-device-in-windows  

  •  Wrong certificate or pre-shared key is set on the VPN server or client
  •  Machine certificate or trusted root machine certificate is not present on the VPN server.
  •  Machine Certificate on VPN Server does not have 'Server Authentication' as the EKU

Make sure correct certificate is used both on client and server side.

In case Pre Shared Key (PSK) is used, make sure the same PSK is configured on the client and the VPN server machine.

Best regards,

Travis

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