No Internet through PiHole

Expected Behaviour:

Set Pi Hole as DNS server in router settings, internet works and devices use Pi-Hole without adds. have 2 pi-holes because router requires 2 different DNS servers

Actual Behaviour:

devices connect to the router but with no internet, cannot access any web pages and Pi-hole says nothing is using it.

Debug Token:

From Pi-Hole 1
From Pi-Hole 2

Your router is offering itself as DNS server:

domain-name: "lan"

From a client that you believe should be connected to the Pi-Hole for DNS, from the command prompt or terminal on that client (and not via ssh or Putty to the Pi), what is the output of

nslookup pi.hole