Zigbee network issues when a lot of Zigbee lights?

[Hedda]

@OleksandrC

I assume that problem is caused by many off-line Zigbee devices. I have a lot of Zigbee lights (about 50) and they are turned off by a classical switch, therefore they are powered off and not available in the Zigbee network. Sometimes, when I turn on the lights, they start flashing like they want to connect to the Zigbee network again.

A problem with device availability appears for these lights, for socket plugs, etc… Is my assumption correct? How to fix it?

I believe that you assumption migth be correct, it could also be EMF/EMI/RMI interference or some bad/rouge device(s) that is spamming the Zigbee network or not routing all messages.

To fix it I would suggest starting by removing the “dumb” switches from your Zigbee lights/lightbulbs that are Zigbee Router devices as those should always have power and be connected permanently. So either replace the “dumb” switches with a smart switch that indirectly control the Zigbee lights/lightbulbs, or repace the Zigbee lights/lightbulbs with a different brand/model that are not Zigbee Router devices (like the above suggested like Sengled lightbulbs that are Zigbee End Devices and not Zigbee Router Devices).

@fleskefjes

Or the more expensive route, use in-wall zigbee switches / dimmers that hook up to the regular switch and regular bulbs.

This is the solution that I promote myself. I only use smart Zigbee lights for corded labs like window labs and floor lambs where it is easier to remove the dumb switch from the cord (or replace the whole cord). For all my ceiling lights and under-counter lights I use dumb lights with smart switches instead.

@OleksandrC

Now Im getting a lot of timeout errors when trying to work with some devices. Sometimes its fixed by itself, sometimes I have to delete and pair it again.
I noticed that some of the devices disappeared from the devices list.

Anyway, what computer/appliance are you running Zigbee2MQTT on and how exactly are you physically connecting the Zigbee Coordinator adapter to it? Using a long USB extender cable to a USB 2.0 port?

Regardless, before you take further actions to troubleshoot any Zigbee issue, make sure you done your best to avoid EMF/EMI/RMI interference by reading and following this → Zigbee networks: how to guide for avoiding interference and optimize for getting better range + coverage

Tip is to add a few “known good” Zigbee Router devices and then re-pair/re-join the Aqara/Xiaomi devices so they will connect through those. Personally, I recommend buying a few IKEA TRÅDFRI Signal Repeater and Aeotec Range Extender Zi. As one of the problems with Aqara/Xiaomi devices is that they will not automatically move to a closer Zigbee Router device if it added later you must manually re-pair/re-join the Aqara/Xiaomi device after to make sure it connects through the newly added Zigbee Router device. Again see this for even better suggestions and more recommendations → Zigbee networks: how to guide for avoiding interference and optimize for getting better range + coverage

You also need to be aware Zigbee is extremely sensitive to EMF/EMI/RMI and the two most infamous sources of interference comes from Wi-Fi radios and USB 3.x ports/devices/cables so make sure you are connecting the Zigbee Coordinator via long USB extension cable and connect it to a USB 2.0 port and not a USB 3.x or USB 4.x port (so connect it via a powered USB 2.0 hub if your computer/appliance that runs Home Assistant only have USB 3.x ports).

It is quite common that a compatible Zigbee devices will not properly communicate, with corrupt mesages being dropped and sometimes not even being able to pair/join due to EMF/EMI/RMI interference.