My network has two gateways, one is a pfSense box that everyone uses. The other one is a TP-Link firewall essentially for tests.
Some machines inside my network need to access a VPN through the Cisco VPN client. If one of those machines is using the pfSense box as the gateway, I experience random connection drops on the VPN. If I am using the TP-Link gateway that doesn't happen.
I've tried changing the MTU in the pfSense box and that improved things a little bit but didn't really solve the problem. I also followed the guidelines for traffic shaping in pfSense and the connections still drop quite often.