My network has dual stack of IPV4/IPv6 and connect to ISP through PPPoE
I have disabled the “Use Peer DNS” In PPPoE Dial and IPv6 DHCP Client
But the ISP’s IPv6 DNS still coming to my dynamic DNS upstream,
I have noticed this problem since 7.11.2, Upgrade to 7.12 issue still existed.
Is that a Bug? I tried to block the dynamic IPv6 DNS in firewall, but that makes my DNS resolve failed(My main DNS running DoH has works well).
I ran into this same issue a couple months ago. RouterOS ignores DNS servers specified by the ISP’s DHCPv6 but it does not ignore DNS servers in the upstream router advertisements coming from the ISP. I suggest creating a new feature request (go to https://mikrotik.com/support and click the Contact Support button) to do this. I did it and they said they’d consider it if there was interest.
In the meantime, I’ve just set a destination NAT rule to rewrite queries going to the ISP’s DNS to my preferred DNS.
/ipv6 firewall nat
add action=dst-nat chain=output comment="workaround for AT&T IPv6 DNS" \
dst-address=2600:xxxx:xxxx:xxxx::1/128 dst-port=53 out-interface=ether8 \
protocol=udp to-address=2a07:a8c0::xxxx:xxxx/128