pihole -up fails with “Could not resolve host github.com” after FTL error, internet breaks when Tailscale is connected

[Soheab]

Expected Behaviour:

• pihole -up should be able to resolve GitHub and complete updates.
• pihole -d should upload the debug log to tricorder.pi-hole.net successfully.

The VPS should have normal internet and DNS access, including when Tailscale is enabled.

• Operating System: Ubuntu Linux on a Hetzner VPS
• Hardware: Hetzner Cloud VPS (4 GB RAM)
• Docker: Not using Docker

Situation:

• Pi-hole installed directly on the Hetzner VPS
• Tailscale installed and used
• No reverse proxy

Limited experience with firewalls or UFW, so misconfiguration is possible

Actual Behaviour:

The first run of pihole -up failed with an FTL-related error.

Since then, every update attempt fails with a DNS resolution error:

  [✓] Building dependency package pihole-meta.deb
  [✓] Installing Pi-hole dependency package

  [i] Checking for updates...
fatal: unable to access 'https://github.com/pi-hole/pi-hole.git/': Could not resolve host: github.com

  Error: Unable to update local repository. Contact Pi-hole Support.

Running pihole -d completes locally, but the upload fails due to DNS resolution:

[✓] ** FINISHED DEBUGGING! **

   * The debug log can be uploaded to tricorder.pi-hole.net for sharing with developers only.
[i] Debug script running in automated mode
    * Using curl for transmission.
    * curl failed, contact Pi-hole support for assistance.
    * Error message: curl: (6) Could not resolve host: tricorder.pi-hole.net

[✗] There was an error uploading your debug log.
   * Please try again or contact the Pi-hole team for assistance.
   * A local copy of the debug log can be found at: /var/log/pihole/pihole_debug.log

No connection when connected to tailscale. Can reach pihole dashboard.

Debug Token:

See above

[darkexplosiveqwx]

Please share the output from the following two commands: sudo tailscale dns status and cat /etc/resolv.conf

[darkexplosiveqwx]

I suggest you take a look at:

Trying to update gravity but get DNS resolution unavailable

Your Issue occurs because pihole is using itself as dns-server. During an update pihole is often temporarily unable to resolve dns. You should configure your pihole to use an upstream dns-server for its own queries( or any server not being itself). If you want filtering / analytic for the pihole machine itself I recommend having a /etc/resolv.conf similar to me: nameserver 127.0.0.1 …

And the whole thread of Pihole with Tailscale DNS error

[Soheab]

That was it. Thanks!