Home Assistant stops repeatedly reloading FRITZ!Box Tools when a router cannot provide traffic statistics. On affected models, requesting four unsupported upload, download and traffic-total sensors made every entity in the integration become unavailable about every 30 seconds.
The integration checks whether those readings are supported during setup and leaves them out when they are not. Other supported controls and readings stay connected. A simulated router reproduced the failure and confirmed that skipping the unsupported sensors stopped the reload loop.