After Full upgrade to Bullseye the pi-hole cannot resolve any DNS just for itself

Expected Behaviour:

Pi-hole resolving all DNS for all clients including itself.

OS: Raspbian GNU/Linux 11 (bullseye) armv6l
Host: Raspberry Pi Model B Rev 2
Kernel: 5.10.60+

Actual Behaviour:

Pi-Hole resolving domain names for all clients but cannot resolve domains for itself (when running apt update, ping google.com from SSH).
This issue occured after upgraing from Debian Buster to Debian Bullseye.
After I add manually the IP for DNS (1.1.1.1) into /etc/resolv.conf the dns resolving for pi-hole is working but after restart the file regenerate itself.
I also noticed that after upgrading to Bullseye my network interface eth0 disappeard / renamed to enx(MAC address of eth) and I assume that is an issue, but i dont know how to solve it.

Debug Token:

https://tricorder.pi-hole.net/InMwmi4Q/

sincerely,

Please note that Debian 11 is not an officially supported OS yet - official support for Debian 11 will likely only be added with Pi-hole's next release.
(EDIT: I'll add that as of today, the latest Raspberry Pi OS image as available from raspberrypi.org is still dating from May 7th 2021, so Buster still. Also, note that he RPi Foundation discourages in-place upgrades to new releases.)
Meanwhile, some users were successful in using the current Pi-hole release with Bullseye, and some encountered mostly minor glitches.

That said, the DNS configuration of Pi-hole's host system isn't altered by Pi-hole.

You should be able to resolve your issue by adjusting your RPi's DNS configuration.
E.g. on Raspberry Pi OS, you could check DNS servers for your RPi's network interfaces in /etc/dhcpcd.conf.

That may contribute to your issue.
Either look to adjust entries in dhcpcd.conf accordingly, or try to use sudo raspi-config to disable predictable network interface names.

Hi, i got the same issue where pi-hole stopped resolving after the upgrade, below is the order i did the upgrade

  1. Upgraded PiHole to the latest version that just got released
  2. Did an in place upgrade to Bullseye

Resolution stopped working. I check my adapters and eth0 disappeared, i disabled predictable interface names in raspy-confit and rebooted. The adapter was still named as enx(MAC). The only way i could get this to work is update the pi-hole.conf file in /etc/dnsmaq.d/ and updated the listening to adapter to the new name.

Adding net.ifnames=0 to /boot/cmdline.txt (append to first line) and reboot should restore the classic interface names.

The normal solution to this is to run pihole -r and select the reconfigure option.

Thank you, this fixed it.

Thanks Michalng for your suggestion as well.

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