Windows IPSec to FortiGates

Hi everyone,

Looking for some guidance. We have a Windows server up on AWS and I'm trying to use the built-in Windows VPN services. I have an IPSec tunnel setup on dual FortiGates in their SD-WAN configuration.

The Windows machine connects, FortiGate shows the tunnel being up, but then the Windows server never completes giving the error "The L2TP connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer." Then the tunnel disconnects.

Any thoughts?

Thanks