Hello I recently purchased 2 packs of 3 Deco P9 for my holiday house, to replace TP-link wifi extenders that were failing regularly.

On first setup, all Decos updated to the latest firmware, so I can't say if they would work better with an older version, I didn't try.

My setup consists in 3 Deco positioned on the same floor, of which one is the main Deco. They are aligned and chained to the next one. The Deco hooked to the main Deco is very stable, the second one in the chain fails everyday.

I have 2 other Deco one floor below, one linked to the main Deco, the other chained to it. They both fail regularly, after a few hours of stable work they disconnect 10 times per day. The last Deco is further down and away in the garden and hooks directly to the main deco (so 2 floors above and sideways)  with only one bar of signal and no PLC, but is surprisingly also quite stable.

I use the mesh network to connect a good number of IoT devices (about 50 clients) and access them from distance. My main issue is that when one Deco fails, it still broadcasts the SSID and some clients try to hook to it and do not switch to another, working Deco. I therefore loose remote connection to them until that one Deco comes back to the mesh. I tried to disable the "mesh" option for some clients when they were connected to the main deco, but it seems it does nothing, the clients continue to roam to other Decos (although they are fixed devices), including those which fail.

I fail to understand why 3 Deco out of 6 keep on failing. I switch different units from the 2 packs, same issue. I moved the decos in different places, no success. The Deco linking to the main deco is litterally below the main deco, one floor below, it cannot be any closer. Floor is concrete with metal bars, which is why I opted for a Deco with powerline capability. All deco except in the garden have the PLC backhaul symbol showing. I verified all electric cabling of the house, it's modern and clean.

For me this looks like a problem of firmware stability. When I get to the web UI the "CPU" bar shows 100% all the time. The traffic is minimal, only a few kbps, so it seems it's busy working around with the mesh management. In despair I have plugged the Decos on smart plugs (it can still do PLC surprisingly) and reboot them every night, but there isn't one day without a massive failure of the mesh, leaving 2-3 Decos offline for most of the day. Their light is solid red or blinking red, it depends.

In term of configuration, I have disabled fast roaming and beamforming. The only option left active is a guest wifi in addition to the main SSID. I have no other option, parental control, or anything like this.

I am now considering downgrading the firmware on all 6 Decos, is there any chance that it can help?

Many thanks for any assistance with this.