How to get session over internet by IP?

I’m stuck trying to make a basic multiplayer game. It works fine locally but I can’t figure out how to get the session variable from a server using it’s IP (not joining, that’s simple).

I want to query the server and get the session variable so I can show the info on the client (THEN the client can join the session). But standard and Advanced sessions don’t seem to have a way to specify which IP to check at.

I’m happy with just using my LAN but I want the server on one computer and the client on another.

Any idea of how to accomplish this or is actually joining the session my only option?