I have the server running on my old macbook, still running mac os x. My network has 2 routers in it, one is a time capsule (which is a network hard disk and router in one box) and the other is a FiOS router. I believe the macbook is connected to the FiOS one directly rather than indirectly through the time capsule. I'm running the server directly via a port forward with no nginx or other reverse proxy. no hamachi.
instead of my shoe size and IQ, I figure some more useful information would be preferred. I managed to get my friend with a the proxy online at the same time as us and it worked perfectly through the proxy, just with some understandable network lag.