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Expected Behaviour:
I setup PiHole when I was only using Ethernet on my Pi. This worked and PiHole was accessible by devices on the ethernet subnet (192.168.3.x) when configured to use PiHole for DNS.
Later I enabled the Wifi interface on my Pi hosting PiHole, using a different subnet range (192.168.2.x). The admin http interface is accessible for Pi via Wifi using 192.168.2.151/admin from devices on the Wifi subnet.
I would expect to be able to reolve DNS queries from devices connected to Pihole over the Wifi subnet but this is not working, they fall back to a secondary DNS server.
Actual Behaviour:
The devices on the Wifi subnet are configured to use PiHole as the primary DNS server but reading the pihole web interface I never see any queries from those devices.
Now realistically this is because I configured PiHole when only ethernet was in use so it will need to know about the Wifi interface. How do i configure Wifi to be enabled in PiHole and keep the working ethernet setup ?
You could try to change Pi-hole's Interface listening behavior to Listen on all interfaces via Settings | DNS.
While this may solve your immediate problems, note that routing is typically done by your router.
Strictly speaking, it wouldn't be necessary to connect your Pi-hole machine via WiFi when it already has a working Ethernet link in order to communicate with clients on a different subnet.
You could either allow routes between your subnets, have your router forward DNS requests or add another IP to Pi-hole's Ethernet interface instead.
If that seems somehow too advanced or your router doesn't support it (which may well be the case), just stick with your solution, but note that a WiFi connection is not as reliable as a cable link, and incurs a bit higher latency.
What is the current setup? Did you first set the Pi up on ethernet on one subnet, then move it to the other subnet with a different interface? Or, are both interfaces active concurrently on different subnets?
You are correct about not needing to use wifi in a typical setup as the router would handle this issue. For me I have been experimenting with Vlan setups on my router so I need this to make it work.
As you suggested the settings - dns - listen on all interfaces worked for me.
Hi jfb, thanks for your reply. I did setup the pi first with just ethernet and then configured pihole. As Buking_Horn suggested using settings-dns- allow all interfaces got thew wifi being used for DNS as well.