Well this has gone from irritating to just weird. In desperation, I turned off the ethernet router and my Mac, and then swapped out the new AirPort Express Base Station with my old D-Link DWL-900AP+ wireless modem. I then turned on the router and Mac. LW now connects and the firewall icon in LW has disappeard. When I put the AirPort Express Base Station back on, the firewall icon reappears. Rather strange since Mac is not using wireless. It's not clear how to turn off the firewall on the AirPort Express Base Station.