Trying to connect to Windows Server 2012 VPN over L2TP.
Server configured to support L2TP using "custom IPSec policy" PSK. All authentication methods are checked off.
Clients are configured to connect with L2TP and is using the PSK for authentication. Tested with settings [Encryption is optional accepting PAP, CHAP, or MS-CHAPv2] and [Encryption is option accepting EAP-MSCHAPv2].
The server has a public IP and all traffic is being routed to it for testing purposes, nothing is being filtered out. I am using two clients, one using it's public IP from another network and one on the same subnet as my server trying to use its private IP. All clients and the server have their firewalls completely disabled. Neither client can use the VPN and both are Windows 10.
I have verified all L2TP miniports are working in Device Manager.
Connection attempt errors:
Client error: Error 789: The L2TP connection attempt failed because the security layer encountered a processing error during the initial negotiations with the remote computers.
Errors in RRAS logs: None(RRAS is configured to log all events)