Three possible issues I can see are:
Norton firewall always needs to be reconfigured for each new version of LW, thus delete previous firewall rule for LW on Norton & re-add it.

Wireless devices have NAT which behaves a little like a firewall. Most nowadays have UPnP which allows the program to request the modem/router to open a port specially for that session. If the modem's UPnP is not a well designed one then it may not work well. In those cases Port Forwarding is the way to go.

Make sure the trouble-some LW on the laptop is not using either the same connection or listening port as the LW on the other computer. Only one port can be used per program on the network. Otherwise the router/modem seems to block that port being used by other programs or computers, restricting itself to one single user & one single program for that particular port.
So .. way to check is ... go to LW's menu bar, Tools -> Options -> Advanced -> Firewalls. Check the ports on both computers & make sure they are different for both connection & listening ports for each LW. Choose a different port if either computer is using same port, choose one between ports 49152 - 65535 such as port 64049. Oh .. if Norton needs a port range for it's firewall, then add the new port setting too. And then try connecting manually using the File menu -> Connect.