I haven't had any issues having to switch modems to bridge in several years.

that being said,

I have the feeling that if the netgear is simply getting the IP from the modem, so NOT making the authentication, then you might check to see if the FW is turned on or off at the router.

Can you ping the IP address of the router, or the one the router is getting? Can you ping port :80 at the external IP address?

Have you been able to use any other external services before, like remote access, messenger, file sharing?

As suggested above, the slingcommunity is great, and fast and helpfull.