I really don't know about 4.8.1 becaus I did'nt use it behind a router. But 4.9.10 has some UPnP properties in it that help it to configure your router firewall and there is a bug in the UPnP whereas LimeWire will work fine fore awhile and somehow it will change your settings in the firewall and LimeWire will not work anymore. It happend to me a few times. But I still don't know if you are using a router. The symptoms are the same as the ones I experinced.

Latter Grandpa