Please follow the below template, it will help us to help you!
Expected Behaviour:
Pihole server running Ubunt 18.04 operates as network-wide ad blocker. Server does not own DHCP, defer to Asus router runnint Merlin.
Actual Behaviour:
When router has pihole IP set as LAN DNS, server can connect to internet, but ads not blocked. No internet on all other devices on network.
Debug Token:
[✓] IPv4 address(es) bound to the wlp4s0 interface:
192.168.1.202/24 matches the IP found in /etc/pihole/setupVars.conf
[✓] IPv6 address(es) bound to the wlp4s0 interface:
fe80::80af:bba5:d35e:3a2 does not match the IP found in /etc/pihole/setupVars.conf (Use IPv6 ULA addresses for Pi-hole)
[✗] Failed to resolve ads.webmastersdirect.com via Pi-hole (192.168.1.202)
[✗] There was an error uploading your debug log.
Since debug upload failed, but I am currently connected on the pihole server, I've pasted the common debug output I've seen in other comments. I've set up the only LAN DNS to be my pihole IP, this is what triggers network-wide connectivity outage. I also have conditional forwarding set up on the pihole.