L2TP/IPsec Client Access VPN with Pre-shared key is not working in TMG

Recently I worked on an issue where the L2TP/IPSec Client Access VPN was not working through TMG. The TMG was configured to use Pre-Shared key for the IPsec policy but the VPN clients were unable to establish the session with the TMG server. In the Event viewer we, got the below error The following error occurred in…