Diagnose a server that’s down (not responding)

When your server stops responding (no one can connect, the panel shows it offline), follow a quick diagnostic method to isolate the cause before contacting support.

Cause / The problem

An outage can come from the server itself (process crash, RAM saturated, corrupted world), from the network (blocked port, Anti-DDoS active), or more rarely from the onesubnet infrastructure. Without a method, you waste time blaming the wrong layer.

Solution

1. Check the status in the panel: Dashboard → your server. The indicator should read Running (green). If Stopped or Crashed, jump to step 3.
2. Check the global status: consult the onesubnet status page (status.onesubnet.com) to see whether maintenance or an incident is in progress on the Paris node. If so, that’s the most likely cause.
3. Start the server from the panel (Start button). If it crashes immediately, the problem is in the server files (faulty plugin, corrupted world, RAM too low).
4. Read the logs: Console tab or the /logs/latest.log file. Look at the last lines before the crash:
   • OutOfMemoryError → not enough RAM, upgrade the plan or lower -Xmx.
   • Caused by: ... from a plugin → remove that plugin.
   • Failed to bind port → port already taken, change it in Variables.
   • Corrupted chunk → damaged world, restore a backup.
5. Check RAM and CPU in the panel’s Resources tab. If usage is at 100%, the server can no longer respond. A clean restart frees up memory.
6. Test the network connection from your PC: ping server_IP and try telnet IP port (or Test-NetConnection in PowerShell). If ping works but the port doesn’t, the firewall or Anti-DDoS is filtering.
7. Check the Gcore Anti-DDoS: if it has detected an attack, traffic may be temporarily mitigated. Wait it out or contact support.
8. Restore a backup if the crash persists after removing suspect plugins/worlds.

If nothing works after these steps, open a ticket and attach the last 50 log lines plus the exact time of the problem — that’s the most useful information for support.