I just realised that you were posting about upload and not download problems... yeah, I have this problem sometimes, other times I can upload OK (downloading seems to cause few problems). Unfortunately I just can't find a way to configure the router to work properly, even after following the instructions in the links I gave above. Both SoulSeek (a completely different client on a different network for file sharing) and LimeWire still show as being behind a NAT router and both appear not to be configured properly.

I think it's a problem with the Voyager 205 router, and from what I've read in other forums no-one seems to be able to successfully open the necessary port. Other people have followed those instructions and still have the same problems (the uPnP feature doesn't appear to work with that particular router). There must be a way...