To achieve the best result possible over your connection:
Test over a wired ethernet cable whenever possible. This will give you the best chance of achieving the max speed that your internet provider is delivering to your home.
If you can't do that, you can still run a test over Wi-Fi, but the results can be affected by things like your distance from the router, the type of device you're testing on, and which Wi-Fi network band you're connecting to (2.4Ghz or 5Ghz).
The test can be affected by other devices on the network, so to ensure you get the best result possible, make sure that all other devices in the home aren't streaming video, running games, or transferring data.