UNet local server setup

Hey everyone, I have a small question regarding UNet networking (The system currently being deprecated).
I'm working on a very small mobile game without real-time requirements in which one of the players acts as host.
I want players to be able to join different matches based on basic 'room codes'. I'm thinking of having them correlate to ports.

I'm struggling to correctly setup the scene which allows players to connect to such servers, and the documentation is a little unclear. Does anybody have any pointers regarding how to setup such a scene?
It doesn't matter to me if it's through the official UNet prefabs or a custom-made system, as well as if it's local-hosted or network-hosted on a server.

Thanks in advance