Hii, I have setup DNS proxy with next dns DOH, my dns settings are as follows.

ipv4 dns is set to auto and it gives the router ip to the clients and the requests are also going over DOH, for ipv6 I have setup SLAAC+StatelessDHCP and for the dns i have setup the ipv6 address provided by NextDNS. The dns requests of ipv6 are not using DOH, for that  I guess I would have to provide the local address of the router as dns but I cant find the local address of the router.