This would mean more if I didn't occasionally see people complaining about their Wi-fi speeds as compared to their broadband speed. I'm not a fan of Wi-fi as there are so many considerations that it makes an apples-to-apples comparison pretty much impossible to construct.
I recently had my new Fire Stick 4K sitting four feet from my router and it couldn't keep up a stream (even when using the supplied extension cable). I switched to 2.4GHz and the performance was better but still buffered. I have nothing connected to the 5GHz side of my router and on the 2.4GHz side I have an Echo, an Ecobee thermostat (Alexa built-in) and an Android tablet (none of them were actively doing something during the test).
Now my Fire Stick is outfitted with the Ethernet adapter and I'm not looking back.
I'm not suggesting that measurements must be made at the modem, but I give less credibility to data coming via Wi-fi connections.