When SSH will not connect.
WHAT TO ESTABLISH FIRST
Whether the machine is running at all.
HOW
Whether it responds to anything, and what the provider's panel shows.
WHAT THE COMMON CAUSES ARE
A firewall rule blocking you SSH service stopped or misconfigured The disk full, preventing login An address change Brute-force protection blocking your address The machine not booted
WHAT TO CHECK FIRST
Whether you are blocked, by trying from a different network.
WHY THAT IS QUICKEST
It is the commonest cause and takes seconds to test.
WHAT CONSOLE ACCESS PROVIDES
A session that does not depend on the network or SSH.
WHERE IT IS FOUND
The provider's control panel.
WHY IT IS THE MOST IMPORTANT THING TO KNOW EXISTS
It is the difference between a fix and a rebuild.
WHAT TO DO ON THE CONSOLE
Check whether the machine booted Check disk space Check whether SSH is running Check firewall rules
WHAT RESCUE MODE PROVIDES
Booting a separate environment with your disk attached.
WHEN THAT IS NEEDED
The system will not boot, or the file system needs repair.
WHAT TO DO THERE
Mount the disk, correct the fault, unmount cleanly.
WHAT TO ARRANGE IN ADVANCE
Knowing how to reach the console, before you need it.
