Fix a Virtualizor slave server that shows offline

When the Virtualizor master cannot talk to a slave server, it shows the server as offline and tasks for its VPSs fail. Running VPSs usually keep working; it is the management connection that is broken. Work through these checks in order.

Before you start

• Root SSH access to the master and the slave, plus IPMI or console for the slave.
• The slave's IP address and the time the problem started.

Test basic connectivity

1. From the master: ping SLAVE_IP.
2. Test the Virtualizor port on the slave (4081–4085 range is used by Virtualizor services; the admin API port 4085 is typical):

nc -zv SLAVE_IP 4085

If ping works but the port is closed, a firewall or the slave service is the problem.

Check the Virtualizor service on the slave

1. Log in to the slave and check the Virtualizor service status (on most installs service virtualizor status).
2. Restart it with service virtualizor restart.
3. Look for errors in the Virtualizor logs listed in the documentation for your version.

Check firewall changes

• Has CSF, firewalld or iptables been changed recently on the master, slave or upstream?
• Allow the master's IP on the slave's Virtualizor ports, and vice versa.
• Check any provider-level firewall or security group.

Check the server key and licence

• In the master's Servers → List Servers → Edit, confirm the slave's IP and server key/password match the slave's configuration.
• If the slave was reinstalled, its key changed; update it on the master.
• Check that the licence for the slave is active; an expired licence can stop management.

Check disk space and load

• df -h on both servers; a full root filesystem stops services.
• uptime and free -m; an overloaded slave may respond too slowly.

Check afterwards

• The server shows online in Servers → List Servers.
• Run a harmless task, such as restarting a test VPS.

Troubleshooting other symptoms

• Online but tasks fail: read the task log in Tasks; storage or template issues are common.
• Comes and goes: unstable network between master and slave, or the slave is overloaded.

Frequently asked questions

Do VPSs go down when the slave shows offline?

Usually not; only management actions fail until the connection returns.

Should I reboot the slave?

Only as a last resort, since it stops all VPSs on it.

Can a time difference cause problems?

Yes. Keep both servers synced with NTP.

Next steps

• Add a slave server
• Panel hardening
• Update and maintenance