A kernel regression in Ubuntu 24.04 (6.8.0-110-generic) is causing networking issues on Cloudron systems.
This regression breaks internal connectivity (hairpin NAT / loopback routing), which can result in symptoms such as:

• Apps being unreachable from within the Cloudron server itself
• Failure to pull images from a Docker registry hosted on the same Cloudron instance
• cloudron-support --troubleshoot reporting: Hairpin NAT is not working
• Docker registry errors like registry error: {"reason":"server error","statusCode":500}

This kernel version is typically deployed automatically via Ubuntu's unattended upgrades after a reboot, you may not have chosen to install it.

Note: This issue affects Cloudron systems running Ubuntu 24.04 (Noble) only.
Users on Ubuntu 22.04 are not affected.

Step 1: Check if you are affected

Run the following command on your Cloudron server:

uname -r

If the output contains 6.8.0-110-generic, your system is affected.

Example affected output:

6.8.0-110-generic #110-Ubuntu SMP PREEMPT_DYNAMIC Thu Mar 19 15:09:20 UTC 2026

Step 2: Fix: Update to Cloudron 9.1.7

The recommended fix is to update Cloudron to version 9.1.7, which includes a patch for the firewall rules affected by this kernel regression.

Update via the Cloudron Dashboard:
Dashboard → Settings → Updates → Update Cloudron

Background

This is caused by a known kernel regression tracked under Debian Bug #1130336.
The regression affects the networking stack in a way that breaks hairpin NAT, preventing a server from reaching its own services through its public IP or domain name.

The underlying fix has been committed to Cloudron's platform:
https://git.cloudron.io/platform/box/-/commit/bffc97ab2fedb06100bc507abd0f8b42d343ea6e

References

Forum topics:

• https://forum.cloudron.io/topic/15419/issue-pulling-custom-app-from-registry-on-the-same-cloudron
• https://forum.cloudron.io/topic/15417/cloudron-down-after-ubuntu-docker-update-docker-service-fails-to-start
• https://forum.cloudron.io/topic/15314/could-not-load-dashboard-website-with-loopback-check-after-3-tries

Debian Bug Report:

• https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1130336

If you continue to experience issues after updating, please create a topic in the Cloudron forum and reference this announcement