Are both LW's using same router? If yes, make sure your LW is using a different connection & listening port to your brother's LW. Under tools > options > Advanced > firewalls.

For new versions of LW, sometimes you need to remove the previous firewall rule & re-add it for the new LW.

Check other options here: http://www.gnutellaforums.com/connec...t-connect.html