If your netgear .router has a private ip (10.x.x.x, 192.168.x.x, 172.16.x.x- 172.31.x.x) on the internet (WAN) port then you will need to do the port forwards.on the cable modem or put it into bridged node.

What ip do you get when you connect a pc (set to djcp) straight to the cable modem?