I guess your router's a Dynex? Can you find the model number?

4.8.1 doesn't have the firewall icon. To find out whether there's a firewall interfering, in LW go tools > options > bug reports > view example. Scroll down to 'recieved incoming this session'. Is it true or false?

Try changing ports. In LW tools > options > advanced > firewall config. change LW's listening port to 64049, or try some in the range of 49152 - 65535. Click Apply to save the change.

You've tried the obvious fixes...if changing ports doesn't help, have a read through this thread & see whether you have this windows update. If your router isn't using UPnP (ie UPnP enabled within the router & the UPnP option selected within LW's tools > options > advanced > firewall config) then AFAIK it won't apply to you.
http://www.gnutellaforums.com/connec...e-anymore.html