@David-TP 

In addition to the network cable connection with the ISP, a Tplink TL-SG108 Switch is also connected.
In this Swtich are connected cabled IP cameras, hub iOT and Alexa.

  @nergruht I noticed this thread has been started years ago but that there are still recent entries. I'll add mine to it.

As of about 10 days ago my 3 Deco P9 unites have been showing similar behaviour. My Deco P9 network has turned all units to solid red status 3 times in the past 10 days, I have had them working for nearly 2 years without any issues.

What happened:

- All 3 unites show as solid red.

- The first time restarting them all in the deco help fixed the problem, but this was the case only once.

- 2nd time around I tried restarting, unplugging and pluggign in the main Deco unit, Unplugging and plugging in all deco units. Restarting the ISP modem I ended up factory resetting all the Deco units AND the Isp modem and reconfiguring my network from scratch. I did swap out the main Deco unit with a different Deco unit.

3 days later I get home... All units solid red again.

This time I tried restarting the units in the Deco Ap, no result.

- I unplugged one of the two not main deco units - I pretty much wanted to eliminate the fact one unit was corrupting the network after a while.

- Unplugged the main deco unit

- Unplugged the ISP Modem, Plugged the ISP modem back in

- Plugged main Deco unit back in, it initially did go straight from Green to red but then surprisingly turned white. The Deco unit that I left plug in went to white status too and after pluggign in the 3rd unit that one got its white status light back as well.

I haven't been paying attention to recent updates

As I am writing this it's August 16th 2022, was there a recent update ?

  @David-TP

Thanks for the swift reply David.

To answer your question. 2 out of 3 times the SSID of the network I set up through my Deco P9 units is still visible but I can not connect to it. Additionaly my DECO app indicates that none of the deco can be be found. So checking the advanced settings was impossible. The time I did check everything seemed to be ok but I will pay closer attentino to the IP4 address next time it happens. That is, if it happens.

Meantime the SSID through my ISP's modem is up as well, can be connected to and does provide me with WAN access.

What I've done for now is number my 3 P9 units and if an other crash occurs I'll set up my network again on 2 units to see if the problem persists. I'll keep repeating the process till all units have been left out of the network or till the problem stops occurring. Since I doubt more than one unit would develop a defect at the exact same time my guess is that there is one faulty unit that is somehow corrupting the network.

  @nergruht  

I have been having the same issue. I purchased this unit yesterday and it worked fine. 

I woke up this morning and all of the lights on the 3 Decos have been red. My internet is absolutely fine and I can connect directly to the router via my laptop/tablet/phone devices. 

I have reset the deco units 3 times as well as unplugging the router the same number of times. 

I have gone into the Deco app and removed the devices and repaired 3 times but literally after about 30 seconds, the light goes red and it tells me there is "no internet". 

If I'm being honest, I wasn't expecting this and am somewhat disappointed in this purchase as I bought the devices after reading about which APs would be best for a Virgin Media Wi-Fi set up - previously I was using Tenda Nova which was not great at all but I didn't have these type of issues. 

Is there someone that can help resolve this asap?

Thanks,