Change ports. That's worked for a couple of Tiscali customers now. No guarantees, but it's an easy thing to do so you might as well try

Within LW go tools > options > advanced > firewall config. Now change LW's listening port to something in the range of 49152 - 65535 (say 64049). Apply > ok. Any ports forwarded thru a router must be the same number as the listening port.