@bernieeccles 

Thanks for the reply.

I have the TLWPA8631P kit and another TL-WPA8631P Powerline ac wifi extender. I have turned off the power saving feature but still as often or not, when I connect my phone to the wifi network which incidentally is configured as a onemesh system, I initially still get something like 72Mbps connection speed but on turning the wifi off then back on (on my phone), the speeds will jump up into the hundreds.

 I have also tried connection with a Samsung tablet and get similar results.

I find it hard to believe that this is how the system is supposed to work. I have also tried connection when my devices are literally 3 feet away from the AX55 router.

  @bernieeccles 

Hi,

A connection speed of 72 Mbps is normally something one would see when connected to a 2.4 GHz Wi-Fi, while connection speeds in the the hundreds sounds more like being connected to a 5 GHz Wi-Fi.

Do you have "Smart Connect" activated in the wireless settings menu of the AX55?

If yes, then you maybe better switch it off. Then delete (or "forget") the original Wi-Fi network on your phone and tablet and re-connect them only to the SSID of the 5 GHz wireless network. 

  @bernieeccles 

I have switched off Smart Connect and turned off the 2.5Ghz wifi and now just have the 5Ghz wifi   broadcasting. This has certainly improved matters and when I connect my phone now the speeds are nearly always in the hundreds and as I move around the house, I can see them alter as they connect via the one mesh system so this corse of action would appear to have solved my problem.

Thanks.