Another vote for this; currently they're hard-coded to Google's IPv6 servers, which means clients bypass my pi-hole and go over to Google. :(

I really need this too. I use OpenDNS to prevent my kids from accessing adult content websites and without the ability to set IPv6 OpenDNS DNS numbers it doesn't work. I can switch off IPv6 and stick with only IPv4 which will work since I can change the DNS numbers for IPv4, but why not offer IPv6 DNS customization too? Makes no sense.

I too would like to see this. I'd love to turn IPv6 on, but I don't want to lose the filtering I have in place with my piHole, and OpenDNS.

I hope others vote for this too. The crazy thing is, it would be a very simple feature to add. I can't believe it wasn't added when IPv6 was first introduced (which frankly, should have been introduced with the first generation eero. Even the over five year old Apple Airport Extreme has this ability).

Google bot give an error with Ipv5 Servers I also receive error through webmaster my  Animation Monster so I suggest you don't try IPV5 Servers

Adding my vote to this request. 

Added my vote to this. Please add soon.

This is a definite must!! Add my vote too

Really need this to use IPv6!

Yup. Me, too. I’ll probably go with Ubiquiti or the Synology mesh router. I need to do some research.

There may be a free DNS Server out there like https://www.videocubix.com/ , but Windows Server has a DNS Server among other server things. Just for DNS though, search for things on Google.