An update:

This morning I started working with a laptop with wifi connection to the basement Deco unit, which sits on the same desk, i.e. the distance is short. Connection was created immediately and it was fast. After about half an hour the speed was dropped dramatically. Because I was mainly reading documents, I just continued working and followed what's happening. The connection was all the time very slow, but there was a connection and my VPN connection to company network was alive.

At some point I also started my desktop pc, which is connected to the same Deco unit with an ethernet cable. This PC couldn't create a connection. I tried ipconfig /renew every now and then, with no luck. There was only a timeout and an error message "no connection to the DHCP server". At the same time my laptop's connection was still alive (barely).The led on the Deco unit was solid white all the time. Deco app didn't find the unit.

After about 2 hours waiting I finally rebooted the deco unit. I unplugged it from the mains and plugged in again. After that (for about an hour now) both the laptop and desktop pc have had a stable and fast connection.

This clearly is a firmware problem, somehow related to the weak wifi connection to my basement. Swapping the units doesn't help and problems are tied to the location, not to a specific unit.

Is there a beta firmware available? I'm willing to give it a try.

@Jaytea 

Hi, I experience exactly the same problem the only difference is that I have a P7, started last saturday.

I bought a new LG Smart TV and connected it with a cable to the primary Deco unit, after a while the internet connection were lost both on WIFI and Cable, after rebooting everything it worked for a while but then it lost the connection again, it takes about 1h-3h and then I need to reboot again.

Any suggestions how to solve this would be much appreciated since my kids is going bananas.....

//Nisse

@TP-Link_Deco 

Hi, thanks for your reply. Here are my answers.

Both satellites have icons visible for both Wifi and PLC. Obviously, when the app doesn't have connect to the basement Deco unit, then I can't check them. Anyway, I have never seen anything else but both icons visible. This has been the case also when the connection is slow, but the app still sees the unit.

Problems useally start after 1-2 hours of usage, sometimes only after few minutes.

I have tried all wall sockets in the room where I need the connection. It seems that this doesn't have any effect.

Booting (= unplugging and plugging the power cord) the basement unit solves the problem, until it starts again. Meanwhile it works just fine.

Waiting doesn't help. I just was away from home for two days. When I left, there was no connection from the basement and the app didn't see the unit either. The led was solid white. After two days, when I came back, the situation was exactly the same.

@TP-Link_Deco I'm having the same exact issue as described by many here, what is the fix? Can you have someone contact me? I just bought 2 of the 3 Pack Sets only 6 months ago and I'm ready to toss them out the window! No one here can work efficiently. I'm using Deco P9's, firmware just updated all units to 1.1.2 Build 20200918 Rel. 74476 (issue occured BEFORE the update, about last week sometime) thinking that would fix the issue. I've tried relocating the units, 4 of the 6 were hardwired but no only the Main unit is wired, this seems to at least keep the connection somewhat stable however my speeds are drastically reduced. Since I deployed them, I was getting ~400Mbps now I'm lucky to get ~100Mbps. I have about 45-50 servers/clients connected at any given time of day. Please help.

@Jaytea 

I'm having this exact issue. One of my satellites (Which my desktop is connected to) loses its connection randomly.My wife's desktop, on another satellite, is 100%. Was working until recently for months. May have corresponded with updating the DECO firmware. M9 plus. 

If I can't get it to stop, I'll get another brand and return them to Costco.

@ImARealMesh 

An update from me... I had contact with TP-Link engineer about a month ago. We had a remote session (about 2 hours) and he investigated my Decos.He found something, did a temporary fix and said they are working on a permanent solution.

After that I've had no problems at all.

Now there's an update available for my Decos but I have not updated yet. Maybe I should contact the same engineer and ask if I should perform the update or not.