FRITZ!Box 6820 LTE Service - Knowledge Base

FRITZ!Box 6820 LTE Service

Installing an older FRITZ!OS (downgrade)

The latest FRITZ!OS provides new and improved functions and resolves known issues. We also continuously adapt and improve security functions to take current requirements into account, which protects you against new, potential threats. Using the latest FRITZ!OS ensures maximum safety in your home network.

It is possible to reinstall an older FRITZ!OS (downgrade). However, for these reasons we do not recommend it.

Important:When you downgrade, the factory settings are loaded, which deletes all of your settings.


  • Windows 10 / 8 / 7 is installed on the computer.

1 Downloading the recovery tool

  1. Call up in a web browser.
  2. Switch to the folder for your FRITZ!Box model and then to the subfolder "deutschland" or "other".

    Note:The complete model name of your FRITZ!Box is displayed in the FRITZ!Box user interface on the "Overview" page and on the underside of the device.

  3. Download the file with the file extension ".exe" to the computer.

2 Connecting the FRITZ!Box with the computer

  1. Use the network cable included with delivery to connect the computer directly to a "LAN" port on the FRITZ!Box. 
  2. Clear all other connections between your FRITZ!Box and network devices or USB devices.

3 Disabling firewalls

ATTENTION!Only disable firewalls when applying the recovery tool and re-enable them before establishing an internet connection. This software protects your computer from attacks from the internet and prevents other threats (for example computer viruses) from being executed.

  1. Disconnect the FRITZ!Box from the internet and do not reconnect it until the firewall is started.
  2. Configure all firewalls on your computer (e.g. ZoneAlarm, Norton Security) so that they are not automatically re-enabled when your computer restarts.
  3. Close any active firewall applications.
  4. Disable the Windows firewall:

    Windows 10

    1. Click "Start" and then "Settings" in the Windows task bar.
    2. Click "Network and Internet" and then "Windows Firewall" in the "Settings" menu.
    3. Disable the Windows firewall.

    Windows 8

    1. Press the keyboard shortcut Windows key + X and select "Control Panel" from the context menu.
    2. Click "System and Security" and then "Windows Firewall".
    3. Disable the Windows firewall.

    Windows 7

    1. In Windows, click "Start" and then "Control Panel".
    2. Select "Category" from the drop-down list "View by:" on the top right ().
    3. Click "System and Security" and then "Windows Firewall".
    4. Disable the Windows firewall.

4 Applying the recovery tool

  1. Run the file "fritz.box_...recover-image.exe" and click "Next".
  2. Follow the instructions.

    Note:It is not an error if the program does not search for the FRITZ!Box under its IP address, but under a different IP address instead. This does not affect the procedure.

  3. If the tool displays an error message such as "Recovery failed due to an error", run it again. If recovery fails after several attempts, run the recovery tool on a different computer.
    • If the recovery tool displays the message "Complete - FRITZ!Box successfully restored!", then the recovery process was successful.