Reliability issues with Shelly wave & Zooz ZST39 LR Stick (Z-Wave JS)


I have strange reliability issues with my Shelly Wave (1pm & Shutter).
As long as I only control one it works fine (for the most part).
But as soon as I control multiple (as little as 2) at once it becomes very unreliable:

  • Sometime nothing happens
  • sometimes only one light reacts
  • sometime one light reacts at once and the other one reacts several seconds later
  • sometime it works just fine

My Setup:
Home Assistant (2024.5.2) on a Raspberry Pi 4
Zooz ZST39 LR (firmware 1.20) plugged with USB extension cable
Shelly Wave 1pm & Shutter
Z-Wave JS

Any idea what the issue might be?

Thanks for your help.

the issue is with the z-wave 700/800 coordinator’s firmware. I have the same problem with 4 Qubino modules and a lots of users are reporting this behavior.

Basically the coordinator get jammed when there are to much trafic on the network at the same time. Yes, 4 lights controlled at the same time is enough to jam the coordinator.

When you send commands to multiples devices at once, the controller is unable ack all devices messages so devices sends their reports over and over (waiting for the controller to ack), flooding the network. This cause lag (lights not responding simultaneously) or in the worst case, the controller get jammed and have to reset, sometimes causing the actions to be lost (lights not responding).

If you search for “z-wave jammed controller” on google, you"ll find a thread about this on SiliconLabs’s forum. SiliconLabs has not yet figured how to fix the firmware causing some users to downgrade from 700/800 series controller to 500 series controller which are not affected by this issue.

On my experience, firmware 7.21.2 is a bit better, but the issue is still there. So the options are to wait for Silabs to fix the firmware or downgrade to z-wave 500.

Adding some delay between each device actions could also help reduce this issue. Also reduce devices reporting interval to reduce network trafic.

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Hello Alain,

thank you for the response and the insight.
It makes a lot of sense.

Interesting development though:
I also have a SkyConnect zigbee stick connected to my Raspberry Pi.
While troubleshooting the issue with the z-wave lights, I disconnected the SkyConnect stick.

Since then, the issue with the z-wave devices is gone.
I triggered my automation at least 75 times and in 100% of the cases, the lights instantly and reliably reacted.
I then re-connected the SkyConnect stick… and the issue is still solved. Z-Wave devices still react as they should (instantly and reliably).

Can somebody explain that to me?