The component for fast.com (https://www.home-assistant.io/components/sensor.fastdotcom/) overlooks that the RPi LAN adapter is limited to 100 MBit/s, and would skew results.

The Speedtest component (https://www.home-assistant.io/components/sensor.speedtest/) has this note:

When running on Raspberry Pi, just note that the maximum speed is limited by its 100 Mbit/s LAN adapter.

I attempted to add this note to the fast.com component, but I'm not great at GitHub yet, and didn't want to fork the entire project for one comment.