@TP-Link 

Well I also updated to 1.6 which was offered by the app on my phone last week.

Last couple of days I have been battling with my smart switches at home. On/off dropping off the network constantly. 

Pretty dangerous since some of them are switches that turn on lights on the stairs.

Deco's are in AP-mode. Raspberry pi does DHCP etc .

Edit seems not only the smart-life things are dropping off the network but while checking the Sonoff switch dropped off the network.

Edit 2 : checking and it's full of IEEE 802.11: disassociated on these devices which was never ever a problem before.

Edit 3 : checking the logs on home assistant my Xiaomi smart stuff is also battling ... like all other stuff on the wifi. The logs are being filled up with them dropping on / off the network.

Edit 4 : The one that is connected wirelessly doesn't have a hostname. Like why?

Turning on guest mode to check cannot be done since the switch is run on home assistant. I can see the log of that one. Seems to be on/off all of the time since I probably switched to 1.6..

And yes : 'MESH' setting is set to off.

Full reboot done

Wifi smart switch reboot done

I have 3 x M5. 2 of them, main and other are connected via cable and have most smart stuff on it.

I should have checked this forum before I did this.

How can I go back to the latest version?  If I can not I would like to get new M5's on version 1.5.

I will be travelling soon and I cannot afford to not being able to control or monitor my devices when not being home! 

  @JanRekenaar 

Jan, I think it is the handover protocol that manages the device to switch to an AP that has a stronger signal.

Check these protocols  IEEE 802.11k/r/v  TP-link to correct me.

In my case. 40 minutes ago I reconnected and switched on my R7800 router and enabled 2.4GHz and the same SSID and pwd as a matter of test.  Disabled the 2.4GHz on the M5.  Guess what. All devices, even 2 floors up with very weak wifi, have been up and running since I have switched the R7800 on. 

Something seriously wrong with this firmware I guess. 

  @Lukesan 

Lukesan wrote 

I reconnected and switched on my R7800 router and enabled 2.4GHz and the same SSID and pwd as a matter of test.  Disabled the 2.4GHz on the M5.  Guess what. All devices, even 2 floors up with very weak wifi, have been up and running since I have switched the R7800 on. 

Can you explain again, why you can't do that same thing with Deco Guest Network? I have smart switches connected to Guest Network that runs on 2.4GHz only, they do just fine with M5 running on firmware 1.6. My Deco mesh runs in AP mode and here is its WiFi configuration:

  @Alexandre. 

Well first of all why would I have to run stuff in Guest mode when it worked perfectly before?

I would like to use the stuff I buy and pay for the way it is supposed to be used for. Also my Guest network uses a different SSID and I still plan to use it as a guest network. 

As I see it now with your configuration there is no automatic switching between 5GHz and 2.4GHz when walking around in area's where 5GHz is not that strong which is also a no go.

  @Lukesan 

Older devices which only run on 2.4GHz sometimes don't handle well dual band and band steering. I run this configuration for almost 2 years, not sure what in firmware 1.6 triggered that issue for your smart switches and cameras, but it is not unexpected to have. 

Your workaround is as good as mine. Even better, when you plan to use guest network. When Deco runs in AP mode, there is always router in front of it with its WiFi, which can be used to deal with issues you described, as a workaround.

  @Alexandre. 

This is not a solution.  The fact that it worked perfectly from October 2020 till now is just proof that it did work and is now causing issues with the new firmware.  There have at least been 2 or 3 firmware updates while I have used the M5's which didn't cause any issues.
The other person with the IP camera's is another example of something that is not ok what worked normally before.

If I have to follow your advice I will have to buy a couple of more other routers just for the smart devices.

Nope, not going to happen. My electricity bill is high enough as it is right now.

Mesh is switched off on the devices as they were before. I also tinkered with assigning them to the nearest AP and especially 2.4GHz. It did not do a thing.

TP link can either fix the issue, offer me a 'down' grade firmware like I had last week or a bunch of other M5's that had that firmware. 

  @Lukesan I am with you. I think that there are too many issues with 1.6.0. This was already the case in the beta versions only a couple of weeks before suddenly the beta version was the release candidate and final version. TP-Link could't even have had the time to fix al these issues.