The automatic update feature was introduced with FRITZ!OS 6.20, meaning you'll never miss another update and you can use new featutes right away. Under "Update" in the "System" menu of the FRITZ!Box user interface, there are three options for regular updating in the "Auto Update" tab.
Automatically update to the new version
The most convenient option is the setting to be notified about every new version of FRITZ!OS and have it downloaded and installed automatically. The FRITZ!Box selects a suitable time for installation, generally at night, and installs the software automatically. Internet and telephone connections are interrupted briefly – after restarting, the FRITZ!Box works with the new operating system.
Install updates automatically
This setting applies only to the software AVM designates as necessary, for example, security updates. As with the first option, you'll get notified when new software is available and FRITZ!Box will automatically start the download. A suitable time is selected so that the installation doesn't restrict your use.
Get notfified about new FRITZ!OS versions
If you select this option, you will see a message that an update is available. This notification will appear on the start page of the user interface, or you can set it up as a push mail. Keep in mind that the FRITZ!Box will continue working with the old software until you perform a manual update. For this reason AVM strongly recommends enabling at least the option for performing necessary updates automatically.