With LW 4.18 you will most likely need fresh gnutella.net file. Also try other suggestions here:
http://www.gnutellaforums.com/connec...t-connect.html
BTW if you still have the older computer & LW in use, I'd suggest you set LW 4.18 to use a different listening port in advanced -> firewalls settings. Reason for this is clash of ports for the router to handle. A router will reserve a listening port for each. Likewise you could try changing connection port also.