I am hosting a couple of services (Matrix chat server and a game server). I know NAT's job is to translate external requests into internal addresses, so that the traffic can hit the WAN and ultimately make it to the internal service which is expected to handle the traffic, however I'm wondering if my setup is correct.

Everything is working as expected, but I'm just wondering how the traffic knows which service to go to. If an outside requests comes in, is it just the destination port that is used to route to the correct internal IP? Do I need to do something else here for best practices?