I am running pfSense 2.4.0-RC which has OpenVPN 2.4 and supports AES-256-GCM. When I try to connect to Switzerland I can connect with AES-256-GCM but no traffic is passed, when I switch back to AES-256-CBC it connects and passes traffic. I can connect to my pfSense box from my computer or phone using AES-256-GCM so I do not think this is a pfSense issue. Is anyone else having problems with AES-256-GCM? I would like to switch to GCM for performance reasons and this super annoying.