Actually, thanks for posting that. I'd seen it before and didn't want to go through with it because I felt like it should be fixed closer to the root since others seemed like they were eventually able to get it going. I'm going to check that out now and report if it works (I tried another supposed fix where setting "stunserver=stunserver.org" in the config to just "stunserver=" helped a guy get it going, and while it didn't work for idol to join up with me, it did eliminate the error message I was getting... so maybe this is a step in the right direction).
EDIT - Nope, nothing. I downloaded the stunserver EXE, threw it in a directory, started it up, changed my UT3 config to point stunserver to 192.168.1.136, changed my ports to forward all the aforelisted ports to the same IP, started the game, and idol still can't join.
EDIT x2 - Okay, now apparently there was a problem with the friend system on UT3, and it wasn't letting idol join because he was trying to follow me instead of trying from the server. So now I don't even know if I needed all this extra shit. Several others joined and the server was fine. Go figure. Gonna' try to remove the whole extra bit and see if just getting rid of stunserver.org fixes it, since that removed the error.
EDIT x3 - Yep. Didn't even need all that extra stuff. Just get rid of stunserver.org from the config and you're gold. So motherfucking simple. What a mess. Thanks though, Scott, for all your help. I learned quite a bit through all this either way. Idol ended up providing the winning link, but it was pretty closely related to what you posted. So thanks again... I appreciate you taking so much time out for me.