@Alexmesh thanks for explaining. I think I've misinterpreted the Deco map screen. It seems that PLC/wifi are being used to access the main Deco. Of course, I can't see if PLC _or_ wifi is being used...

Here you go... I think i can see the wire/wifi logo on the lines here, so does this mean the 2 other units are PCL/wifi? @Alexandre.

@Alexandre. Yes, that's true of course, but the "main" Deco has PLC and so it should be able to use the power grid of the house too, yes? I just wanted to make sure that the main Deco unit could use...

@Alexmesh Thanks for the reply. I emailed TP-Link support and they just told me that the main unit ("Loft" in your case) does not show the PLC/wifi indicator, so it seems that we cannot know if PLC...

@thelinkuser Any ideas @Alexmesh ? One more question - should the PLC logo appear on the "main" router if it is plugged in to the mains properly? A few people have asked this on the forums. Thanks...

@thelinkuser Here is a screenshot below. The extension cable I looked at was: https://www.amazon.co.uk/dp/B0CH78NNTR/ref=pe_27091411_487029541_TE_SCE_dp_i2