Something for the network professionals: DNS not reachable when VPN active

[Nachtwesen]

Expected Behaviour:

I, along with others, have been looking for a solution to my problem for 8 hours. I have been using Pi-Hole for many years. PH is on the latest version and runs wonderfully. This is so when no VPN is connected and also when I use Cyberghost or ProtonVPN (all Windows 10, latest version). The Pi always responds to all DNS requests.

Since today I use NordVPN and no matter what settings I make, it no longer works. If I use the native OpenVPN client it works, but never with the NordVPN client, whose amenities I would of course like to use.

If the VPN is connected I can ping the Pi, everything works, but DNS requests it just returns a "timeout". "nslookup google.com 192.168.0.24".

It almost seems to me, as a layman, that the Pi is reachable but the NordClient is somehow blocking port 53 or something. I also talked to support for a very long time and they seemed to have a clue. That ports are blocked is not known there.

I am confused and really appreciate any ideas from you guys to get my beloved Pi Hole working again. Thank you very much.

Actual Behaviour:

No DNS answers from Pi-Hole when VPN is connected via NordVPN CLIENT(!)

Debug Token:

https://tricorder.pi-hole.net/dBrYcnoN/

[jfb]

@Nachtwesen

Since today I use NordVPN and no matter what settings I make, it no longer works

With almost all commercial VPN services, when you connect to them and set up a VPN tunnel, your DNS traffic moves to their DNS server and stays within the tunnel. This is done to prevent a DNS leak, where your data traffic is secure in the tunnel but your DNS traffic is exposed outside the tunnel.

[Nachtwesen]

Thanks for your quick reply. But I have always managed to use my PiHole with all the other VPN providers, even though that may have meant less security. I can also ping it, so that's possible and in the network settings the Pi is also entered as the first DNS server. But he can not answer. How can I do this?