How do you run a useful business speed test?
Test where the problem occurs. Then compare the result with a wired test near the router. Repeat the test during your busiest time. One good result does not prove the connection is reliable.
Why do Wi-Fi and wired results differ?
Walls, distance, interference, channel use and client devices affect Wi-Fi separately from the carrier circuit. If the wired result is strong but Wi-Fi is weak, inspect the wireless network first.