If LImewire just stopped working without anything at all being changed, then it sounds like your ISP and not your setup.

But anyway it should be enough to just forward one port in the router to the server IP, since your computer is directly connected to it. Choose some high number (64049 seems to be a popular choice) so it doesn't interfere with other tasks. Then just change both the listening port and forwarded port in Limewire to 64049.