Sonoff S31 Lite Plug misbehaving since

My Sonoff S31 Lite plug that has been working fine for several months started misbehaving concurrent with my update from (or .38, not sure) to It is possible this is just a coincidence, but regardless, the S31 Lite is misbehaving.

The S31 Lite controls 2 lights.

  • When I go into the HE Room Lighting App to the rule for the light plugged into the S31, I see an X in the "State" field, indicating the S31 Lite is not connected to the Hub. However, if I click on the X, it immediately connects, and I can turn the light on and off.
  • When I go into the HE Room Lighting App to the rule for the bulb NOT plugged into the S31, but which relies upon the S31 as a repeater to get the Zigbee signal to the bulb, I see an X in the State field. Again, if I click on the X, the bulb connects (presumably through the S31 Lite, but I don't know how to check that) and I can turn it on and off.

10-30 minutes or so after doing either of the above, both devices will disconnect from HE so the automations associated with turning them on or off stop. If I again logon and click on the X, HE instantly connects again.

Nothing has changed in my house (no recent additions of anything metal, no new computers, no moving furniture around) and nothing has changed in my setup (no recent new devices, etc.). The only thing that changed is the update to the hub, and immediately after this issue started.

Any ideas what I can do to fix it?

The bulb and the S31 Lite are the only two Zigbee devices I have. I bought the S31 Lite to act as a bridge so the bulb would connect more reliably. Everything worked for over 3 month....

That is pretty much what it is.

Your zigbee mesh is very weak (there's no mesh to speak of), so it is very susceptible to minor changes in the RF environment. Did you or any of your neighbors change WiFi channels? Did you add any new BT devices?

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I did none of those things. No idea about the neighbors.

So I need more Zigbee devices? What a pain. I'd prefer Zwave as it is so much more stable, but the only Zwave bulbs I could find are Inovelli, but at 3x the cost of Zigbee, I figured Zigbee would be fine. Zigbee sure does not go very far - the plug is within 15-16' of the hub, and the bulb is within 8' of the plug....

I think it depends on how many devices you have .... I have one large zigbee mesh (85 devices), one medium size zigbee mesh (~35 devices), and one large z-wave mesh (62 devices). I can't distinguish them in stability or performance.

There are too many variables to measure distances in linear feet.


There are several reports of S31 Lite ZigBee performance issues - weak repeating, mesh instability. Anecdotally, I have two and they were never a significant part of my mesh.

Again anecdotally, one S31 failed to trigger from a rule yesterday. As initial triage, I swapped it with a spare S40 and plugged the S31 in a different location. The new location is nearby, but rotated 90 degrees on 2 axes. It is suddenly a prolific repeater in my mesh, suggesting that the antenna may strongly favor specific directions.


How do you determine what role a device has in your mesh??

Do you mean how many devices it is repeating for (assuming it can repeat)?

The simplest way would be to look at the output of the endpoint:


The most informative way would be to use an Xbee3. You can put one together for about $30-40, with the added bonus that they form very good repeaters.

Or…he could just add a Sonoff Zigbee 3.0 dongle, Hue outlet or two, or those inexpensive plugs you have recommended in the past. I complained on here before about the Sonoff S31 lite being terrible repeaters but they have been reliable as far as staying connected and working. I have 12 other strong Zigbee outlets and in-wall switches as well as 3 Sonoff dongles on the same hub though.
Another thing that I noticed a long time ago was that until you do a firmware update, or shutdown the hub and reboot, the child devices don’t seem to change much after adding devices. When I bought my second HE hub and added all of my Lightify 4-button switches to it before any repeaters, they remained child devices of the hub until the next firmware update.

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What would a "Sonoff Zigbee 3.0 dongle" attach to?
Which "inexpensive plugs you have recommended in the past?" What is the brand of even one of your "strong Zigbee outlets"

Regarding your statement that "the child devices don't seem to change much after adding devices" - I'm not sure my Sonoff S31's are "child devices?" They do not appear as "sub" devices in the device list like other parent/child sets. But your comment "....until the next firmware update" might explain - I did an HE firmware update then all this started...

@danabw has created detailed instructions on using Sonoff zigbee 3.0 dongles as repeaters, linked below:


@danabw has created detailed instructions on using Sonoff zigbee 3.0 dongles as repeaters, linked below:

Thank you. But I still don't understand what the dongle attaches to. Looks like it has a USB. To what device do I plug in that USB?

Any USB power supply that provides at least 0.5A at 5V. Most phone chargers would work.

I use these Sonoff dongles outside my house. One in the garage to detect when my car is approaching (I have a zigbee arrival sensor in the car), and the other on the front porch to receive signals from a contact sensor in my mail box. They are really good repeaters, and the transmit power can be set as high as 9 dBm.

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I guess I'll need to add that to the guide. :slight_smile:


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I read that the new dongle e defaults to 20 dbm transmit power.

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