# DoH via ISP not working after fresh install

**URL:** <https://discourse.pi-hole.net/t/doh-via-isp-not-working-after-fresh-install/77508>\
**Category:** Help\
**Created:** [March 5, 2025, 4:32pm UTC](https://discourse.pi-hole.net/t/doh-via-isp-not-working-after-fresh-install/77508 "2025-03-05T16:32:37Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![dfd78](https://discourse-cdn.pi-hole.net/letter_avatar_proxy/v4/letter/d/5daacb/32.png) [@dfd78](https://discourse.pi-hole.net/u/dfd78)\
**Post date:** [March 5, 2025, 4:32pm UTC](https://discourse.pi-hole.net/t/doh-via-isp-not-working-after-fresh-install/77508/1 "2025-03-05T16:32:37Z")

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Hello all

- operating system: Raspberry Pi OS Lite "Debian GNU/Linux 12 (bookworm)"
- hardware: Raspberry Pi 3B+
- setup: DoH using the process described at [https://docs.pi-hole.net/guides/dns/cloudflared](https://docs.pi-hole.net/guides/dns/cloudflared)

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 [https://docs.pi-hole.net/guides/dns/cloudflared](https://docs.pi-hole.net/guides/dns/cloudflared) - everything was working fine. I had them both set up to use my ISP's DoH server which is listed at [https://www.aa.net.uk/dns](https://www.aa.net.uk/dns) as [https://dns.aa.net.uk/dns-query](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 [https://docs.pi-hole.net/guides/dns/cloudflared](https://docs.pi-hole.net/guides/dns/cloudflared) 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/](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/](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!

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**Author:** ![Bucking\_Horn](https://discourse-cdn.pi-hole.net/user_avatar/discourse.pi-hole.net/bucking_horn/32/18719_2.png) [@Bucking\_Horn](https://discourse.pi-hole.net/u/Bucking_Horn)\
**Post date:** [March 7, 2025, 12:18am UTC](https://discourse.pi-hole.net/t/doh-via-isp-not-working-after-fresh-install/77508/2 "2025-03-07T00:18:26Z")

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

Please see [Issues with using cloudflared as upstream DNS server](https://discourse.pi-hole.net/t/v6-post-release-fixes-and-findings/76480#:~:text=Issues%20with%20using%20cloudflared%20as%20upstream%20DNS%20server).

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**Author:** ![dfd78](https://discourse-cdn.pi-hole.net/letter_avatar_proxy/v4/letter/d/5daacb/32.png) [@dfd78](https://discourse.pi-hole.net/u/dfd78)\
**Post date:** [March 7, 2025, 12:57pm UTC](https://discourse.pi-hole.net/t/doh-via-isp-not-working-after-fresh-install/77508/3 "2025-03-07T12:57:46Z")

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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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**Author:** ![system](https://discourse.pi-hole.net/uploads/default/original/3X/7/c/7c8792f649eeb921c5d2b4c41564ffa873d9a2b8.png) [@system](https://discourse.pi-hole.net/u/system)\
**Post date:** [March 28, 2025, 12:58pm UTC](https://discourse.pi-hole.net/t/doh-via-isp-not-working-after-fresh-install/77508/4 "2025-03-28T12:58:36Z")

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