OpenVPN - connections disconnect even with keep-alive set to 0

[PatrickMooreSA]

Hi all

I hope there is a simple solution here - I recently upgraded this firewall from 23.1 to the latest 25.1.5, and I now have OVPN connections dropping every 40 seconds. The server has keep alive interval set to 0, but the clients keep disconnecting. This is tested on Windows 11 with OpenVPN Connect 3.6.0 and OpenVPN GUI 2.6.13.

I have compared the config with other OpnSense Firewalls on the same OS version, and all settings are the same, but the others do not experience disconnections.

What am I missing?