Hello there,

I purchased 3 x Brand New TP Link Deco P9's Powerline from an Authorised seller on eBay on 30th September 2020. They worked so well I purchased another 3 x Brand New TP Link Deco P9 Powerline's from Amazon on 15th October 2020. I had 6 Deco P9 Powerline's all working together great in my house. 

We have an Out-Building that is on a separate powerline, so my P9 Deco's would not work there. So I found some selling 3 x TP Link Deco E4 on Facebook Marketplace, only 5 minutes from where I live. They said they were only a few weeks old, and they were selling them due to their new Router coming with WIFI extenders. 

So I got the Deco E4's home, reset them and added them to my Mesh Wifi System through the Deco APP. I Set the first Deco E4 up no problem, placed it in our outbuilding and it worked well with my P9's. I then set up another Deco E4 through the app, which seemed to work as well. I placed the second Deco E4 which I had just set up, in my kitchen, about 6 Meters away from 2 Deco P9's. 

I started to notice that my Deco P9's, that were nearest my E4 which was in the Kitchen. Started dropping the Internet and the Red flashing light was coming on them quite often. Which had never happened before. I checked my other 3 x Deco P9's and they were working fine. My Deco P9 which is plugged into my Router was working fine, and no flashing Red light was appearing. 

I then started to move the 2 x Deco P9's and Deco E4 around my house, as they kept dropping Internet, to see if that would make a difference. I plugged the 2 x Deco P9's and the E4 into my Office, where the router and the main Deco, which is plugged into my router are located. This did seem to fix the problem, so I then moved the Deco P9's and E4 to where they were located originally, and this did seem to fix the problem for a few hours. Then they started flashing Red again.

I then plugged the Deco P9's & E4 back into my Office. They were flashing red, then going to white, and then flashing red again. This has been going on for a couple of days now. 

I rang TP Link Technical Support, they have opened a ticket and they told me just to monitor the situation. Which I have been doing. 

I have decided to remove and unplug both TP Link Deco E4's. Even though the first Deco E4 I set up, seemed to be working fine with my mesh system. It was just the second one I set up, which seemed to be causing all the problems. 

My original 6 x Deco P9's seem to be working fine now, but I will continue to monitor them. 

I'm not sure if the Deco E4's I purchased are faulty or malfunctioning. I assume there are still under there 3 Year Warranty. 

I really hope any one can help.

Kind regards