P9 - Powerline Backhaul Intermittent Connections and slow speed

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P9 - Powerline Backhaul Intermittent Connections and slow speed

This thread has been locked for further replies. You can start a new thread to share your ideas or ask questions.
P9 - Powerline Backhaul Intermittent Connections and slow speed
P9 - Powerline Backhaul Intermittent Connections and slow speed
2021-12-19 15:16:02
Model: Deco P9  
Hardware Version: V1
Firmware Version: 1.1.3 Build: 20210115 Rel.60510

I'm having intermittent Powerline connections between my Deco P9s, and have tried pretty much every solution on the forums with no avail.


Would be grateful if someone can shed some light?



My Network

I have 2 M9 Plus, and 3 P9s, all operating in AP mode.


Both M9s and 1 P9 is connected via Ethernet, directly to the Router - so generally speaking, they don't need a Wifi overlap to operate. And of course, they work just fine.


The "Living Room" P9 has a medium-strength WiFi connection, and is on the same socket loop as the Office P9 - that is, both of these sockets are connected to a single fuse on my Electrical Board, so they are on the same single wire loop.


The Shed P9 has a very weak WiFi connection to the Kitchen M9, but is on the same overall electrical circuit for the house, as the other P9s.


The problem is that the PLC connection status of the P9s seem to drop out at least 2-3 times a day, with no explanation. When the PLC connection goes - Shed is just offline, Living Room will work if it has a Wifi Signal at the time (sometimes not, so it goes offline too), while the Office P9 keeps working thanks to the Ethernet backhaul.


I have tried the following:

- Upgrading the firmware of the M9s and P9s via the app's autoupdate

- Manually updated the firmware of the P9s with the latest dev build I could find on the Community Forums (on the thread about similar issue)

- I have switched the placement of the Office and Living room P9s to various different sockets

- I have switched the Living Room, Office and Shed P9s themselves - to rule out a dodgy unit

- I have used all 3 P9 units (while connected to Ethernet) as the Main Deco [cause support docs say PLC is only active with P9 is the main deco, not true]

- I have switched my 2 M9s as the Main Deco [PLC on the P9s do come on with either of them as the main Deco]

- I thought maybe PLC drops out if there is no activity on it, so to the Shed P9 (where only the PLC connection should be regularly available), I connected a Ring Indoor Cam (which could not pick up Wifi signal from any other Deco Units except the Shed P9), and set the Camera to take 1min snapshots - i.e. a data transfer via PLC at least once a minute. And no, that didn't help either.



In summary - PLC works, whatever the connection setup / main deco / physical location of the devices, but only for a while. PLC drops several times a day, and then re-establishes itself after a while - with no rhyme or reason!


I have also attached the Debug Log from the Shed P9 for reference.



For reference, M9s are running the firmware: 1.5.1. Build 20210126 Rel:59387


The Other Problem - P9 Speed


I'm sold that M9s need to be my main Deco, as the P9, regardless of this PLC issue, has terrible speeds.


Sitting about 1.5 metres away from a Ethernet linked P9 with no obstructions but air, and about 8 metres from a Deco M9 (+ 2 ceramic tiled drywalls between us), I get:

 - About ~130Mbps on Ookla Speed Test when an M9 is set as the main Deco [on a Samsung S21, via Ookla's Android App, connected via 5Ghz wifi]

 - About ~50-70Mbps when the P9 right next to me is set as the main Deco


Between those tests, no changes were made to the network, router config, etc. 


Even the tests, which are of course running against Public servers so can be unreliable, were repeated 3 times each against 3 different servers - M9 first, and P9, and then M9 again just to be sure.


I know the M9s have a greater overall bandwidth, but ~130Mbps should have been childsplay for the P9s advertised 867Mbps 5Ghz connection.


So something is going wrong there


2 Reply
Re:P9 - Powerline Backhaul Intermittent Connections and slow speed
2021-12-21 09:34:43


Hi, thank you very much for the detailed information.

It would be very helpful if you could provide us with a rough drawing of the floor map about the location and distance between Deco units.

So that we could check whether we could relocate the Deco unit to improve the performance.


As for the PLC backhaul, I have checked with the engineers and there is an exception that when one P9 is on the Ethernet backhaul, another satellite P9 is wirelessly connected to it and it has the chance to create PLC backhaul.

But normally, we would suggest using P9/P7 as the main Deco if you wish to maintain a stable PLC connection.

Re:P9 - Powerline Backhaul Intermittent Connections and slow speed
2021-12-22 13:38:40

@TP-Link You said if one P9 is on Ethernet backhaul, a second may try to use PLC to it?  Can you confirm this please, as that is the configuration I want.  I want my X20 which is acting as a router, to provide ethernet to a P9, which can then provide PLC backhaul to a second P9


Does that work, and what firmware version is needed for this?



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