I've played around with my own home network for a long time, and I know what kinds of problems can arise just in the network itself. But this is a strange problem. I will set up a gatherer to get a game going and I'm only able to join from a single client. A second client will attempt to join and the request will just time out. Even if the first client quits and then the second client tries again, it still won't work.
I have to quit to the main menu on my server and then start the server up again, then the second client could join, but the first will not be able to after the second joins. Can anyone tell me what is going on?