A router itself can act like a firewall. You need to read the instructions that came with your router & use the advanced functions on how to open up a port (ie: port 6346) After doing that, you need to go to LW's Tools-Options-Advanced & Firewalls & tick Force IP option box & enter 6346 if it's not already listed.

http://www.experts-exchange.com/Netw...utions_13.html (I think article 320 but there might be more such as http://www.experts-exchange.com/Netw...utions_13.html)