Server Troubleshooting

Permission denied (publickey)

Their key is not installed, the file permissions are wrong, or their username is not on AllowUsers.

Check all three, in that order.

Works by IP but not by the .ts.net name

MagicDNS is off, or that device never accepted the tailnet invite.

Worked for weeks, then stopped

The server’s node key expired. Disable key expiry in Tailscale — see Step 7, item 4.

This is the failure that arrives about 90 days in, long after you have stopped thinking about setup.

Random disconnects when several people are on

Out of memory — the system killed a process. Run free -h. Add swap or move to a larger plan.

Caution

This looks like a login problem and is not. People lose hours here re-checking keys and SSH config when the actual answer is memory.

“dubious ownership” when using Git

git config --global --add safe.directory ~/bos

Claude Code icon missing after connecting

The extension was installed locally instead of in the remote window. Reinstall it using the Install in SSH button — see Connect Your Editor.

Locked out completely

Use the Hetzner console’s built-in Rescue mode. It gets you in without SSH.

This is why the guide is ordered the way it is — but if it happens anyway, you are not stranded.

Everything after setup

For the system itself rather than the server, see Troubleshooting.