Yup, it looks like the R7000 won't let you configure its DHCP server to use anything other than itself as the DNS server. In that case, you could enable DHCP on the Pi-Hole instead, as @Mcat12 suggested here:
Yup, it looks like the R7000 won't let you configure its DHCP server to use anything other than itself as the DNS server. In that case, you could enable DHCP on the Pi-Hole instead, as @Mcat12 suggested here: