The linksys wrt54 is unreliable in UPnP mode which is why a special trick needs to be done to overcome the issue that UPnP is failing. So hopefully the fix will work for you also. I previously saw the same fix on a gaming site. But didn't want to post it on this forum because if novices tried it & put in the incorrect details then they could muck up their router. So I don't normally recommend such fixes as cracking the normal firmware.