I don't have Norton AV so I can't confirm the settings. Someone else could.

As for your device, I'm not sure if your device supports UPnP. You'd need to telnet into it & check to see if it does have the option. If not, then forwarding a port is the answer. Port forward instructions are here Port Forwarding for the Motorola SBG 900; Telnet address is http://192.168.100.1