I think you are getting good advice, and I can't say I fully understand the Option 1, 2, 3 stuff from the other posters, but I will tell you my experience:

1. Prior to AT&T, I used cable internet service with v3 firmwear of the same Netgear router you have. I would get cable model + netgear set-up and there followed random mis-connects, requiring powering (Cable model, router, PC down, rest, and back on in sequence. Router was set to report by PC's MAC address to cable service, but due to a defect in the router, it would lose the PC's MAC and not be able to report it back to the cable provider, thus requiring the lengthy reset dance to temporarily fix. It was a common and well-known defect in Netgear routers of the make at that time at least.

Currently, I use an AT&T wire DSL interface box with D-link DI-604 router for the past year with no problems. Router worked out of the box with no fuss at all.

Lost internet, three days ago when Microsoft's latest pushed security update and ZoneAlarm software firewall would not play nice. Quickly, fix by lowering Zone Alarm's firewall setting to "medium" and they issue their own proper patch yesterday.

FIRST thing, I do with connection problem is taking out the router from between the AT&T interface box and the PC. It that fixes the problem, then the problem is the router. AT&T seems to accept hardware routers and firewalls as normal; cable said "Bad! We don't support routers/firewalls."