I agree with johnnienucleo, because like you said, it stems from using a new router and it worked before. Some routers from Linksys have problems with letting Limewire through when using UPnP, that's why just trying to forward the port is a good idea.

There are firmware upgrades and hacks for most routers, but there are no guaranties that it will work, while if you get forwarded properly, your problems are gone forever... or at least to your next hardware change comes up