The Big Fritzbox update has arrived: you must do one thing first
Once the password has been assigned, click on “Save”. The backup now needs to be confirmed, which can be done either via a phone connected to the Fritzbox or by pressing a button on the Fritzbox itself. On a phone, enter the number sequence displayed, for example *18653. If it worked, you can save the backup locally. You will then find a file with the extension “.export” on your system.
By the way, restoring a backup is just the opposite. There is a “Restore” tab on the Fritzbox for this purpose, where you feed the export file again, for which you need the password. Note: You can restore the full backup on the same Fritzbox model, on other models only part of the backup may be available, depending on the range of functions.