C6220 Parental Controls not working

I am having the same problem with my new Comcast/Xfinity service with a Netgear C3000-100NAS router.

All my clients are bypassing the OpenDNS IPV4 DNS settings, and using the Comcast IPV6 DNS servers, rendering the OpenDNS filtering useless.

Does OpenDNS support IPV6 DNS? They say they do and supply IPV6 sand box addresses here:

https://www.opendns.com/about/innovations/ipv6/

2620:0:ccc::2

2620:0:ccd::2

are the IPV6 Sandbox DNS servers.

Now, how do we enter those in out Netgear Routers? The web interface on the firmware i have only supports entering IPV4 DNS addresses.

And will that fix our problem? I don't think so, see this note at the bottom of the sand box page on the link above:

Note: IPv6 support in the OpenDNS Sandbox is limited to standard recursive DNS initially. Additional functionality, like Web content filtering, malware and botnet protection, phishing protection, and more will be available on different IPs when IPv6 support is added to the OpenDNS Dashboard. We have no plan to ever shut down or change the default features for the sandbox IPs.

So, I think we may be screwed until netgear updates firmware (or perhaps we can set it up via ssh? I haven't tried this yet) so the web interface support IPV6 DNS entries, and until OpenDNS supports web filtering on their IPv6 addresses.

Is there a way to set up our routers to NOT pass any IPV6 DNS servers via DHCP?