WRT54's have buggy firmware, so yes port forwarding is best option.
Only one software firewall should be active. They conflict otherwise and result in less security, not more. So choose between Norton & McAfee.
Try turning all of momentarily & see if it connects, if it does then it's something with your settings that is at fault.
Norton FW needs to have the firewall rule deleted and replaced each time you update LW or Norton.

Cox is not as innocent as they pretend to be.

Make sure you use a different connection and listening port to the other LW your wife uses. That is very important.

If your router is port forwarded, then your LW firewall setting should be also set to manual port forward.
But you say your router is set to UPnP when you port forwarded. ?