If you have recently installed Comcast Business Class and your network has run afoul after installing and configuring their Cisco or Netgear routers, you may have IPV4 & IPV6 DNS and DHCP problems.
After a new installation of a Comcast issued Netgear router ( I specifically asked NOT to have the Cisco installed because I have had similar IPV6 issues with Cisco), lo and behold, same problem.
After disabling IPV6 and setting the DNS server in IPV4 to use our local DNS, neither one of the two settings are taking effect. So why give the user access to router then?
As you can see by the images, the router settings are useless. The Comcast routers continues to offer IPV6 DCHP and use their own DNS servers in IPV4 and IPV6. Don’t bother to call them, resistance is futile. The best course of action is to bridge the router and use your own router/firewall.