Just check and make sure that you only have one firewall working, having more can cause a conflict and leave your computer vulnerable...
It could be a security update that has changed the configurations of your firewalls, so you really need to have a look at each of them and see what is running and what is not....
Also maybe something has reset in your router, check your UPnP and see if it is still enabled, also you can try Port Forwarding to see if that helps...
I can't find the instructions for the RT41P2 but here are the instructions for the RT31P2.....
http://www.portforward.com/english/r...2/Limewire.htm
I also found this site it may help you work out what is going on with your router...
http://www.retrevo.com/search?q=Link...=review+manual