FYI: You're testing Wi-FI & WAN. Wi-FI is independent of WAN. Install OpenSpeedTest on the Flint v2 or use iperf3 to bench Wi-Fi performance.
The quality of radio chip sets across devices is massive. They seem to becoming more & more biased towards downloading instead of bi-directional through-output but I don't spend a lot of time testing Wi-Fi for the former reason. Usually Intel cards, both Wi-Fi & wired, give the best shot at getting the closest to up/down rates as manufacture advertised at both endpoints.
This assumes any congestion from neighboring APs is under control, of course.