A more reliable solution may be to use Pi-hole as the DHCP server, and add a dnsmasq configuration file to manually assign selected clients a DNS other than Pi-hole. Then, there is no interaction between Pi-hole and this subset of clients.
A more reliable solution may be to use Pi-hole as the DHCP server, and add a dnsmasq configuration file to manually assign selected clients a DNS other than Pi-hole. Then, there is no interaction between Pi-hole and this subset of clients.