Hi everyone,
I am having the same issue with my multi-sensor Sonoff SNZB-02 and Conbee 2 device. The Conbee 2 is already working well with another device (Aquara door sensor) but after I paired the Sonoff sensor with Phoscon, it would actually work during only a few hours and after that, both the temperature and humidity would remain constant even though I know they aren’t.
Going back to Phoscon where the device is listed, and I can read the last update is from several days ago. It’s like no temp/humidity data has been pulled since that time, event through it should have.
Any idea what’s the problem?
Can it be installed with a different method than the deconz addon in HA?
Thank you
I have the same issue with a Conbee 2 & Zigbee2MQTT…
And also with the SNZB-04 devices, but less often.
I did a video on the SNZB-04 and mentioned in it that I bought three. One drains the battery in a matter of days, one just stops responding (light doesn’t flash opening the door) and so I have to re-pair it. Am dropping the Sonoff devices and replacing with Aqara ones. I was running Conbee II with deConz, tried with Conbee II and ZHA, now using Sonoff Bridge with Tasmota and ZHA, still getting issues with the Sonoff SNZB-04. My Aqara sensors have been reliable so will switch from Sonoff to Aqara.
As an FYI, I just learned of a January 2021 update to the zigbee radio firmware for the Sonoff Zigbee Bridge. The update version is ncp-uart-sw_6.7.8.
see Tasmota/tools/fw_SonoffZigbeeBridge_ezsp at development · arendst/Tasmota · GitHub
This update fixes battery drain problems with IKEA Zigbee devices.
I wonder if it will fix the disconnection of the Sonoff SNZB-02 temperature sensors?
Some caveats of the update process are mentioned in this thread.
The key to the update is to change the Module type to 75.
All I did was change the Module type to (75), in the Tasmota Configuration page, and then was able to upload the new file without upload errors.
After the update, you then need to switch the Configuration back to the custom configuration (0) so it will function as a Zigbee bridge for ZHA, again.
Thanks for the details. My Sonoff had already been updated with the 6.7.8 radio firmware and the battery issues were still hit or miss along with a few other ‘quirks’.
I bought one of the Tube Coordinators with ethernet on it and received it today and re-paired all my devices. A few were a PITA about getting on the network and I went back and finally deleted my zigbee.db and started again fresh. Things seemed to go better after that.
Have one device that keeps jumping off the network and I need to work through that issue still. I have plenty of routers in the network and the mesh is looking pretty good.
We’ll see how this goes - the Tube hardware ended up costing about 3 times as much as the Sonoff, but if it solves the problem, I guess it is worth it. The Tradfri remotes seem to pose a bit of a challenge to ZHA once in a while.
I’ve also had a bunch of issues with the Sonoff PIR’s and Temp sensors (Sonoff SNZB-02)
Dropping out, consuming batteries in a month and have always had my Conbee II on an extended USB cable, conversely the Aqaras have been fantastic. The Sonoff Windw/Door sensors have also been pretty good overall 1 out of 6 failing completely.
My advice stay away from them, they’re cheap and nasty.
Not wanting to necro this thread but I wanted to chime in on my experience as well. I have the same issues with the Sonoff SNZB-02 together with the Sonoff Zigbee 3.0 USB Dongle Plus V2. No battery drain or anything but just random disconnects where I have to fully delete and pair the sensor again in order to make it work.
I got a couple of window sensors as well, those work like a charm. But the temperature sensor is just unreliable.
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I have same issue with my SNZB-02. It just work some time and after just stuck at last value of temp and hum. I try to use it with zigbee2mqtt and tuya but same behavior. Most tragic is that I bought a lot 20 devices and they work all in the same way 
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I also have/had issues with SNZB-02 + Sonoff Zigbee Bridge (though curiously not in another setup with the Sonoff USB Dongle).
The sensor would lose connection with the bridge every day or so and need repairing.
Then I replaced the CR2450 battery with two AA batteries using this sonoff temperature sensor battery hack and since then the sensor kept its connection - fingers crossed it stays that way.
Maybe the lower internal resistance of the AA batteries helped the matter…
Its 2 years later and the Sonoff SSNZB-02 on combee 2 is still constantly disconnecting. I moved all my devices from Deconz to ZHA but that has not helped. I have 5 temp sensors and it feels like im constantly finding ones that have disconnected and manually reconnecting them. Batteries say they are low but they are not, replace them anyway, they still become unavailable or just stick at one temp for weeks.
All my other slSonoff, Aqara, Ikea, and Philips Zigbee devices are working well. Its just the sonoff temp sensors.
I think i might need to replace them with Aqara sensors. 
Certainly the most unstable Zigbee devices I have ever experienced. Whatever I did, they left the Zigbee mesh after some time. Until I reflashed them with the EFEKTA-Firmware. See my post here. Since reflashed with this alternative firmware I have never experienced any disconnects again. Might be worth a try.
If you are not into soldering I recommend you to take a look at the low cost Xiaomi Mija LYWSD03MMC. Converted to Zigbee they work very reliable but note that battery life will only hold around 6 month before you have to change the CR2032.