Probably a stupid question, but something that just occurred to me - does PLC backhaul only kick in when the deco in question is too far from the main unit to work over Wi-Fi?

Previously I'd commented that PLC worked, I updated, it no longer worked and the furthest unit from my main unit daisy chained off another unit. 
Now it is connecting directly to the main unit, rather than chaining, but signal is weak - just wondering if I moved it a few more feet away would PLC kick in?

  @Dracon Morning, I've got a similar support call scheduled for tomorrow morning. Have been asked to install a debug firmware which is updated from my previous support session. Also involving the RD team so hopefully if they find something on yours then that should hopefully match on mine. 
I've only got a few more days before I'll have to return the units to Amazon or I'll miss my return window. 
I did try something on the sky boxes to switch off wifi on the main box and sky mini. It was already using Ethernet but thought it might help reduce interference, it may no difference to the operation of the PX50 units though. 
 At least it's being looked at now though. 

  @Chuckoir I think the PLC should kick in if the signal is weak as it should be the best route for sending a stable signal back to the main unit. 
 There's not much information to go on though as nothing is documented on how it should work. 
 Might try moving one of the units down the shed as it's on the main circuit and should connect back. 

  @Chuckoir okay did move the office unit down to the shed. While the unit shows as connecting to the main unit it doesn't show how. 
 The wifi signal strength is weak but the download speed and stability allows me to stream at 10Mbs with no issues. 
 The Deco app does not show switching to PLC but the Office unit is about 60 to 70 feet away from the main unit in the lounge. That signal would be going through two old internal walls and and external wall before it even got out of the house so it must be using PLC but there is no way to prove it. 
 As mentioned on another post I have a support call tomorrow so will feed this finding back as well. 
 

  @ommoti 

Interesting! Let us know what the support call identifies, if anything!

  @ommoti 

We're 3 hours in and they are still on it - there's not much happening on the laptop anymore so I can only assume they are updating firmware on their end.

I have a couple of weeks more for my Amazon return window but I imagine if TP-link has requested a return, the window shouldn't matter. It will be a shame though because their previous generation of powerline products worked (well-ish?)

  @Dracon I have been given a remote support session offer just need to confirm it when I'm next free (preferably when the house is empty).

I carried out an experiment last night, I ran an extension cord from the garage to the back of the garden and into the summer house and tried some speed tests with and without the powerline connected in there. There was a noticeable difference with it connected but it makes me wonder if it's just the PX50 having a great and modern wifi system or if it was actually using the powerline and just not reporting it in the app.

According to google earth the distance was 28 meters in a direct line to the closest deco in the house with the last 9 meters being indoors with regular household obstructions.

I've noticed other issues, my VDSL2 FTTC speeds have dropped since I've started using the PX50's not sure if they are interacting and causing noise on the line and also the roaming doesn't seem to work all too well I have to manually turn the phone wifi on and off to get it to connect to the closest point.

Could do with more options in the app to control these maybe VDSL filters and the ability to choose roaming thresholds as although the client device decides the deco can still send out suggestions. I've been at the end of the garden and devices have been holding onto the deco in the house vs the closer garage only switching when the connection to the house has dropped.

  @ommoti 

That's interesting, you say you have 10Mbs, is that what the deco app tells you or via a third party speed test?

When I first connected my third deco on the opposite end of the house to the main deco it connected via WiFi but no connectivity - so even though my phone was connected to it's WiFi I couldn't connect to the internet or to the server which is wired to the main deco.

After a few minutes the furthest deco will then daisy chain via the intermediate deco and provide a reasonable connection for the furthest deco, but it definitely does not connect via the PLC backhaul, and there is a drop in connection speed at the furthest deco commensurate with having to pass through three solid walls.

I've tried a separate power line ethernet connection as the backhaul for the furthest deco and the speed is much higher.

Anyways, will be monitoring this thread, not a deal breaker for me but good when it works

Final update - Had my second remote support session at 9am this morning and that went on till 1pm.
To be fair to support they downloaded a lot of support tools and went through a lot a steps, downloaded a different debug firmware and gathered a lot of information through the putty logs. 
 The outcome of which ended with a final message saying that they couldn't track down the issue and to return the units back to Amazon.
A little sad that the issue couldn't be tracked down and still not overly clear why its not working but it looks like I'm going to send the units back and get a refund.

 Will now need to track down a similar priced whole home mesh network unit that could improve the coverage in the back bedroom.
 

  @ommoti That's dissapointing, did they verify that the units were indeed using wifi backhaul and just not reporting on powerline status? My test with a long extension power reel eariler in the thread has made me think that it could secretly be active in the background but the app doesn't report it.