It sounds like a router issue. You will need to do port forwarding for your router & LW to allow port 6346 access. To my knowledge, it can only be done for one comp on your network so the others (if they also use p2p) would need to port forward using a different port no. See this for a detailed explanation (I use D-Link 504G so I'd guess the process will be identical):
http://www.gnutellaforums.com/showth...threadid=29463