Sonoff sensor SNZB-02P dropping off Z2M network

I have got 15 Sonoff SNZB-02P temperature & humidity sensors on my Z2M network running on Home Assistant Green using the Sonoff CC2652P dongle. I’m also using an Ikea signal repeater which seem to have better signal strength than the dongle and so some devices (including those in question here) connect to that on the network map even if they are physically a bit closer to the Sonoff dongle.

I went with the Sonoff sensors because of a bad experience with the more expensive Aqara sensor and because I liked the large battery.

They have worked well for the first month but recently three have dropped off the network and show as ‘unavailable’. If I press the pairing button they show up again, but report a fixed temperature and then later drop off again.

I’m not sure how to go about diagnosing the issue properly, so would appreciate any advice.

I’m hoping that it’s something to do with how my network is set up and that it can be rectified, but I fear it is just not a reliable piece of kit…

Thank you

What other mains powered Zigbee devices do you have on your network ?

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Mains devices:

  • Ikea smart plug
  • Another cheap smart plug,
  • A relay for the boiler
  • About 15 Ikea bulbs.

The bulbs are on dumb switches so come on and off a lot, but they are not shown in the link on the network map to any of the offending sensors, which all go through the signal repeater.

I also run ZHA on a separate dongle (SkyConnect) with about 3 devices on.

(as an aside, my reason for running both ZHA and Z2M is I started with ZHA but found it was much easier to publish messages from AppDaemon via Z2M, so moved all my devices I wanted to publish to onto Z2M. It had crossed my mind to put the sensors on ZHA instead as no need to publish to them, but I’d need to add repeaters to get good coverage).


This might be part of the problem. When you power on and off router devices, the mesh tries to heal itself from the router devices that went away and end devices that might have been using those router devices will try to find a new path to the coordinator. This isn’t a fast process and can lead to orphaned end devices, especially those built with cheaper Zigbee radios.

The mesh map is a point in time reference, so it would be hard to assume that the bulbs that are being switched on and off weren’t possibly router devices for the sensors that dropped off the mesh. My suspicion here is that the sensors were using the bulbs as routers and then couldn’t rebuild their routes properly.

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Thank you for your thinking. This leaves me with a couple of questions:

  1. Is there a way to supress the bulbs operating as routers. I don’t need this functionality but I do like having them on dumb switches (alternatively, I suppose I could run them on a separate network).

  2. What’s the best way to rescue an orphan? Is it as simple as repairing? Even when they seem to be connected they don’t send any updates, the signal just flatlines.

Thanks again!

Not really. Mains devices (unless specified by their specs) are always going to route messages in the mesh. You idea about running them on a separate network might be the way to go here. Or, replace your dumb switches with decoupled smart switches. I did this with all my mains switches. :wink:

The only way to rescue an orphan is to unpair it and re-pair it again. In terms of the not sending any updates, that could be a flaw of the sensor itself. You mentioned that you press the pairing button once on them, you might need to actually go through and hold the pairing button down to get the device to completely unpair it from the mesh and then allow it to go through discovery again. In the most drastic case, you might need to actually remove the device from the Z2M configuration.yaml file and let it go all the way through discovery. I don’t know enough about the Sonoff Zigbee devices to really answer that.

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