After dealing with this for about 2 years now, I caved and purchased a ASUS router.
All my DNS issues are gone.
Shame on Netgear for not addressing the problem they created with one of the firmware updates. Regardless that the model is old, if a firmware is updated and it causes an issue, the onus is still on them to fix it.
I have tried older firmware, resetting the router and starting over, all the IPV6 suggestions. It was clearly a dns forwarder related problem in the device, proven by using static host tables and dns settings on some of the hosts which helped somewhat.
