Wireless router right? Yes that's a well known problem when using torrents. I am aware the wrt54g has firmware problems & is not reliable. Is it port forwarded? If not, that might be the best way around it. It looks as though UPnP is dropping out now & again due to the extra load of messages.

And yes, in torrent circles they often say they need to reboot their wireless router. The bandwidth is inconsistent for a start, and overload of messages can wreck havoc with the router. Other than port forwarding, not sure the best answer. There is a 3rd party firmware fix to the router but not recommended to novices because you risk rendering the router unusable if get it wrong. (For more about the firmware fix, see Connection problems? Check here first! (click on link) under the UPnP section, under Linksys called " Linksys WRT54G - Fixed my problem, Followed these steps and it works!".)