Tailscale App (v1.84.3) on TrueNAS SCALE 25.04.1 - tun0 interface won't appear, completely stumped!

Apps and Virtualization
1

Hey everyone,

I’ve run into a really stubborn problem trying to get the official Tailscale app (v1.84.3) working on my TrueNAS SCALE 25.04.1 servers. I have two machines, one’s my main production box and the other is a new remote server for backups, and both are showing the exact same baffling behavior.

Basically, Tailscale itself seems to start up fine – the app shows “Running” in the UI, it authenticates and gets a Tailscale IP (confirmed via tailscale ip in the app’s shell), and even the logs say it’s “Creating WireGuard device…” and “Bringing WireGuard device up…”.

But here’s the kicker: when I run ip addr show inside the app’s shell, the crucial tun0 interface is always missing. This means no VPN tunnel actually gets established. Naturally, I can’t ping the machine’s own Tailscale IP, and any attempts to connect from another Tailscale device (like for SSH key discovery) fail because the server is unreachable on its Tailscale IP.

I’ve tried everything I can think of:

  • I’ve confirmed the tun kernel module is loaded on the TrueNAS host (lsmod | grep tun confirms it) and set up an Init/Shutdown script to make sure it loads persistently after reboots.
  • The Tailscale app is correctly configured for “Userspace” networking with “Host Network” unchecked.
  • I’ve verified that the Docker container for the app actually has the NET_ADMIN Linux permission (sudo docker inspect confirms it), which should allow it to create network interfaces.
  • I’ve done complete app uninstalls, generated fresh new reusable auth keys, and performed full system reboots between reinstall attempts on the non-production server, but nothing seems to get that tun0 interface to appear.
  • Even checking dmesg on the host during startup doesn’t show any obvious errors related to tun device creation failing.

Since both my TrueNAS SCALE machines are doing the exact same thing, I’m genuinely stumped on what else to check. Has anyone else experienced this specific issue with Tailscale on TrueNAS SCALE 25.04.1, or have any insights into why tun0 might refuse to show up despite everything checking out? Any help or ideas would be hugely appreciated!

2

I doubt that anyone can still help you with this since your truenas version is more then 2 years outdated and the whole apps backend switched from kubernetes to docker.
I tried to find something in the old forums at TrueNAS Community but wasn’ able to find an older post.
It may be that this is a problem with the truenas tailscale app that got fixed in newer versions, but you will be unable to update to a newer truenas version without having to rebuild your whole apps. Since June 1st. this year there’s no longer an automated update from the old kubernetes apps backend to the new docker backend used since electric eel 24.10.

3

LarsR, thank you for your thoughts. My mistake, my version is 25.04.1, it is a fresh install of Scale to help me debug this issue.

I have to figure out how to modify my original topic :slight_smile: