Really? hmm... I didn't have to update my config any. Also, I don't think you can get a nat problem if you are playing over lan... methinks he's trying to host over the internet still.
If I don't forward - NAT restriction
if I do forward - no problem
It isn't a "real" LAN. It is making a fake one and I would assume it therefore has to use an internet protocol. I am willing to concede this point if someone knows better but this is how I understand it until now.