Ok final thought before you call it in as faulty, is could it be due to hub location.
Is it close to something that reflecting or blocking the signal. So move it around within the limits imposed by the coax. A WiFi scanner on the iPhone will tell you signal strength, as another check.
My 5kHz speed halves once there is a wall in the way
I have a metal mesh music stand and my Asus access point really does not like having to beam through or around that. Glass and metal are the things to check for, or anything rebroadcasting on the same frequency. The roku 2 boxes do that, annoyingly, and I read reports of that causing bad interference. A WiFi scanner will detect that.
Post the links to the tests results here. A few different tests from Thinkbroadband would be good for comparison.
Move far away from the hub/router into another room and test. There's a form of wifi interference which can happen when you are close to the router, or in the same room. Each of the signals bouncing off the walls cancels each other out. This is not a conclusion, it's information.
Your test results so far suggest each device is operating at 54Mb link rate. That can happen due to interference, but also other reasons. The settings may help identify which direction to go.