If the port test doesn't work, it means that LW's default port (6346) is blocked.
You could try going to a higher port (in the range of 49152 - 65535). You'll need to change LW's listening port number within tools > options > advanced > firewall config. You'll also need to change the port numbers allowed through your software firewall. Sometimes changing ports helps, but not always if it's an issue with your ISP starting to block p2p.

You could always give your ISP a call & ask why port 6346 is blocked. They might have changed their p2p policy recently?
Have you tried using any other p2p apps?