DoH via ISP not working after fresh install

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1

Hello all

I have 2x RPi 3B+ running Pi-Hole on my network.

For a couple of years they were both using DNS over HTTPS which I set up using the process at cloudflared (DoH) - Pi-hole documentation - everything was working fine. I had them both set up to use my ISP's DoH server which is listed at Andrews & Arnold's DNS over HTTP (DoH) and DNS over TLS (DoT) service information as https://dns.aa.net.uk/dns-query (I trust my ISP way more than Cloudflare, Google or any other DoH provider).

This week I did an update on one of them (I do one at a time in case something breaks) and it broke the system. Attempts at repairs didn't work so I did a fresh install of Raspberry Pi OS Lite, Pi-Hole — both of which were substantially newer versions — and then followed the process again at cloudflared (DoH) - Pi-hole documentation again to set up DoH.

As soon as I completed set up, the new Pi-Hole stopped responding to DNS requests from the network.

Through swapping out my ISP's DoH server and Cloudflare's again and again, I have confirmed that it only breaks when it's set up to use my ISP's server. It works fine using Cloudflare's.

However, my ISP's DoH server is definitely working. My second Pi-Hole — on the same network, but still on an older version of RPi OS Lite and Pi-Hole, has the same DoH configuration. The only difference as far as I can tell, is that on the newer setup, it breaks when using my ISP's DoH server, and works if I use Cloudflare's. I have shut down each Pi in turn to ensure only one Pi-Hole is running at a time, and both work fine — only the new one breaks under the conditions I described above.

Debug Token:

debug data from the new Pi-Hole that breaks when I add my ISP's DoH server: https://tricorder.pi-hole.net/wJUNRzPz/

debug data from the other Pi-Hole (running on an older version of RPi OS and Pi-Hole) which is working with my ISP's DoH server: https://tricorder.pi-hole.net/VEWvtB7v/

I'd really prefer to use my ISP's server on both Pi-Holes. Can anyone suggest why this issue is occurring?

Many thanks!

2

It seems likely you are affected by issues caused by mIxEd case queries.

Please see Issues with using cloudflared as upstream DNS server.

1 Like
3

Correct!

Adding no-0x20-encode to the misc.dnsmasq_lines in All Settings -> Misc in the web interface fixed the issue.

Thanks so much.

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