Advanced Sessions Plugin

Dedicated servers don’t use the steam client at all, they also need to be specifically built for via a special build target (requires a soruce copy of the engine and modifications). If you are trying to connect to a dedicated server that is just a normally packaged project then it won’t work, you will have to use a standard client server instead.

Try this guide

I already know all of this. Steam has its own Server Browser and if you have steam enabled on the client then you are unable to connect to the server. I can connect using OnlineSubsystemNull perfectly fine. It’s only steam that doesn’t work.