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Expected Behaviour:
the dhcp server of pihole, which i am using does not give the right ipv6 dns to my phone.
Actual Behaviour:
the phone which uses wifi keeps on getting the ipv6 dns from the ISP modem, and that can't be disabled.
ipv6 is switched on in pihole.
I had however an older version of pihole that worked even with ipv6
Well I find out myselve that blocking ipv6 traffic outbound to port 53 is the solution. In any case better then buying another modem, which is not possible in this case because it is a 500mb docsis moden that is provided bij mij ISP.