Whilst you were able to connect before, you had a firewall problem, so either OSX firewall or the router were not set up correctly, else, the firewall was coming somewhere between your computer & your ISP. Having that firewall problem was not good. Now you can't connect at all, and port 6346 is totally blocked. How port 6346 suddenly became blocked sounds suspicous. Generally it's the ISP at fault.

BTW something I forgot to mention before is your model of Linksys is a "lemon" as it has a firmware problem which Linksys never bothered to fix. The effect is unreliable operation, thus occasional undesired firewalling & sometimes maybe loss of connection. Whether your router is at fault here I don't know. I'd be interested if you can connect with LW by by-passing the Linksys router & just using the modem. Try it & see what happens.

If it does connect, then the problem is with the Linksys. If so, then remove your port forward rules for it. Redo them but choose a port between 49152 - 65535 (a good one to try is often port 64049.) Add this port number to your OSX firewall setting, else do another LimeWire one. Also change the connection & listening port numbers in the LW preferences settings. If you "cannot connect" when "not" using the Linksys, then do above anyway.