Your Router does have a Nat Firewall, so give Port Forwarding ago...
These are your instructions...
Port Forwarding for the Linksys befw11s4v2
Also try deleting the limewire preference folder (if port forwarding doesn't work)...This will reset your configurations back to default and get rid of any corruption that may of happened...
Fixes for Limewire when LW isn't operating as it should