Configuring the backup FortiGate
If required, change the firmware running on the new FortiGate to the same version as is running on the primary FortiGate.
Enter the following command to reset the new backup FortiGate to factory default settings.
You can skip this step if the new FortiGate is fresh from the factory. But if its configuration has been changed at all, it's a best practice to reset your FortiGate to factory defaults to reduce the chance of synchronization problems.