@Ninto 

Hi,

Do these mobile devices get higher speeds when connected to other 2.4 GHz wireless networks?

It is still somewhat common for not-so-expensive mobile devices to show bad performance on the 2.4 GHz band.

  @woozle 

Hi

Yes they do.  My phone gets good speed from our existing network.  It's just the tp-link network which is the problem with phone and a tablet so far.

  @Ninto 

Also I have a tp-link wifi extender tl-wa850re that performs better than the powerline wifi (to my phone).

  @Ninto 

I see. The wireless specs of the TL-WPA4220 and the TP-WA850RE are similar, so the speed of the phone should also be similar.

When you tested the download speed on the phone and tablet, was the laptop also connected to the TL-WPA4220 at the same time?
I remember some time ago one user here reported slow download speeds on a device, only to find out later that a computer connected to the same Wi-Fi had been pulling large Windows updates in the background, which affected the download speed of the other device.

  @woozle 

Hi 

I've now tested WiFi upstairs with a Motorola phone and the speed is good.

So it would seem to be a particular problem between the powerline wifi and Samsung galaxy s10.

However my s10 works with a tplink repeater which you said works in the same way as the powerline wifi emitter?

Any ideas.

I am yet to test if powerline works downstairs.

  @Ninto 

There could be some rare incompatibility between the TL-WPA4220 and the Galaxy S10.

Besides, can you please check if the Wi-Fi of the TL-WPA4220 is broadcasting its signal on a different channel than the TP-WA850RE?
In case it is, then one last thing you might try is to set the TL-WPA4220 to the same channel number the TP-WA850RE is using, although I don't expect it to make much difference.