Not sure if anyone can help, i have pihole and used to have a BT Smart Hub with IPv6 enabled.
I have my PC manually set to pihole's IPv4 address, ipv6 still worked and my PC used pihole's ipv4 in Nslookup.
I have since changed to a BT Smart Hub 2 and with the exact same setup but the PC seems to be prioritising using the IPv6 address of the hub for dns over the pihole ipv4. I suspect the new hub is advertising with dhcp differently. This does only seem to happen at the moment on windows device and not android etc.
My pi hole runs on Ubuntu Server with IPv6 set to DHCP, My router is IPv6 stateless. I have since set the IPv6 address as shown in the pihole web interface on the pc and seems to be working again now. Is this the correct way of pointing my PC to PIhole now?
netsh interface ip show dnsservers
Configuration for interface "Ethernet"
Statically Configured DNS Servers: 192.168.1.6
Register with which suffix: Primary only
Configuration for interface "Loopback Pseudo-Interface 1"
Statically Configured DNS Servers: None
Register with which suffix: Primary only
netsh interface ipv6 show dnsservers
Configuration for interface "Ethernet"
DNS servers configured through DHCP: fe80::<redacted>07%10
Register with which suffix: Primary only
Configuration for interface "Loopback Pseudo-Interface 1"
Statically Configured DNS Servers: fec0:0:0:ffff::1%1
fec0:0:0:ffff::2%1
fec0:0:0:ffff::3%1
Register with which suffix: Primary only
PC IP is on DHCP with reservation like before although its the same if manual set, The IPV6 dns address in the photo is the one displayed in pihole web interface.
It would be normal that IPv6 capable clients would prefer to communicate via IPv6.
It doesn't seem like your router would advertise its own IPv6 address as local DNS server, since your output suggests that Windows is using your Pi-hole's IPv6 as IPv6 DNS server address.
To be sure, you could run
sudo pihole-FTL dhcp-discover
which should list no other IPv6 addresses than your Pi-hole's.
If that would mean that it's only offering Stateless DHCPv6, disabling Stateful DHCPv6 as well as NDP RAs (router advertisements), then that could explain why Android would not use Pi-hole's IPv6 address: Android does not support DHCPv6 at all, only NDP RAs, so it cannot not learn a DNS server IPv6 address.
If you want other clients to not use IPv6 for DNS, you'd have to configure your router accordingly, i.e. disable Stateless DHCPv6 as well, in addition to disabling Stateful DHCPv6 as well as NDP RAs.
