Minimal set-up for Unity Transport

I’m trying to test some basics multiplayer functionalities with unity multiplayer services, like creating a lobby, joining it, starting host and client… tweaking settings on NetworkManager and UnityTransport…

I would like to know, if I’m NOT using relay, what I need to set up with unity transport ? Do I just need to joint the lobby and start the client ? or do I need to set up some ip adress and port manually ?
I don’t think testing multiple instances on the same machine can help to clarify this so I’m going to test this right now on 2 pc but I’m not sure what is happening even if it’s works. Like is there a fallback with relay transport ? Can I check what type of transport I’m using during a session ?

network super noob here.