Update from Boxleitner:
I've been running Demigod with /serverproxyonly since Frogboy first suggested it, and have been able to play a great number of games online. I have all firewalls down and have forwarded the correct ports.
However, there are still people I cannot connect to. They appear as green 0ms speeds on my screen and in the connection information screen THEY connect to me but I cannot connect to them. Either of us rejoining the lobby does not help. Waiting for a while does not clear the issue. People still avoid or kick me from their games on site because of this. Even my friends are distressed with me because I create connectivity issues which result in having to kick people from the lobby! 
I've been trying to tell those players who i cannot connect to that they should use /serverproxyonly as well, but I don't think they are listening to me. I also do not know whether, at this point, that will help.
I'd appreciate more information andany advice I can get.
Sincerely,
Box
