Z-Wave Woes (Zooz Zen21)

I just installed my first two z-wave devices (Zooz ZEN21 On/Off Switch) on a smartthings hub and it was an awful experience.

Reading through the forms I see a lot of people saying hey my X number of z-wave devices went offline/not responded or I could see the status updating but not control the device. I worked with support and spend x hours removing and rebuilding my devices/rules to get it working again and now its down again.
I’m new to smartthings/ZigBee/z-wave and from what I’ve read z-wave is more stable than ZigBee but my ZigBee devices while not perfect at least came back online.

Based on what I observed and my IT experience it looks like issues between the versions of Z-wave protocol running on the Smartthings hub and the device.

My smartthings hub (v2, US customer Rev E) is running 18.00022 which is using Protocol Version: 3.83)
The Zooz is running zwv:4.05 lib:06 cc

What is the roadmap/timeline to bring smartthings to v 4.x standard?

I observed many flaky issues all related to handshake type issues:

  1. Rebooting just the hub makes the z-wave device totally not respond to a re-association request. No status updates or device control.
  2. Rebooting the z-wave device (trip circuit) semi brought the device back online. I can see its correct on/off status but I cannot control it.
  3. Removing the device via the android app makes it disappear from the hub with a successful removal message but it is not did-associate on the remote device. I had to do a second round of general device exclusion and saw the device disassociate and reset. I could then finally add it cleanly but any reboot of either the switch or the device but it back in a fubard status.
  4. The good news is that turning on the breakers to power up the switch while the hub was rebooting brought everything back without a reblast of the devices/rules.

I see there was a mandatory memo issued on the “Security 2” framework

Are these types of voodoo issues due to bugs in the code due to a rush to meet the, Z-Wave’s technical certification program deadlines or is it due to smartthings being so far down rev? These look like classic handshake / I don’t know you type issues.


Begin totally non related Rant:
Why does Bixby/Samsung connect not control all devices attached to smartthings? Samsung should be embarrassed that both Google and Amazon can do it and they cannot…

I can’t speak to your Specific case, a lot of people have been having a lot of problems with connectedness over the last couple of months. But it shouldn’t have anything to do with the new S2 standard. That only applies to brand new devices applying for certification, not any existing devices. Once a zwave device is certified, it remains certified, no matter how many new features are introduced in future generations.

And per the standard, all zwave generations have to be backwards compatible, so the brand new devices are supposed to still work with the older devices as well. You just don’t get the kind of version mismatch issues that you’re hypothesizing with Z wave because of this. From the beginning, the standard has required backwards compatibility for all changes.

From the memo you linked to ( emphasis added)

As of today, April 2, 2017, Z-Wave’s technical certification program, which is administered through 3rd party test facilities in Europe, US and Asia, will check that all S2 security solutions, which contain rules for command classes, timers and device types are correctly implemented in every new certified device.

From the certifying body, Z wave alliance:

Will Z-Wave Plus products work with classic Z-Wave products?
Yes, Z-Wave Plus products are fully backward compatible with classic Z-Wave products.

So…no rush to comply with new versions, and shouldn’t be a necessity either.

I know none of that eases the pain of a frustrating install, but it’s not likely a version issue.


BTW, one small note: “Association“ has a very specific technical meaning for Z wave, and I don’t think that’s what you were talking about in your note. You just meant an initial add to the network, right? That’s just called “joining“ or “including.“ “Association“ and “Deassociation” Is an entirely separate process with a separate set of network commands.

I just mention that because association did change significantly with the newest generation of Zwave, and it did cause some complexity when mixing devices of different generations. But the specific model you mentioned, the Zooz Zen21, only supports the minimum level of association, the lifeline group, which is the same as older generations and shouldn’t have caused any problems.


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I’m just tagging @TheSmartestHouse on this as they have the most experience with the zooz Devices and might have some more ideas.


Thanks for the tag @JDRoberts. Just to clear things up on S2 - Zooz switches are not equipped with this feature, neither is the ST hub to our best knowledge since as @JDRoberts mentioned, the standard is only required for devices FIRST certified after last April.

From what you described @Ex_Newfie, it looks like you’re having communication issues which may have to do with range. If you’re only have 2 Z-Wave devices, the network’s mesh capabilities are rather modest and you may just need a couple of repeaters along the way to improve performance for the switches. Depending on the construction and interference in your space, the range, even for Z-Wave Plus devices, may be compromised. Feel free to contact our support for further troubleshooting: https://www.thesmartesthouse.com/pages/contact-us


I would recommend you to pay attention and buy z-wave PLUS devices. I did few mistakes when i started few month ago and bought z-wave (not plus), had some problems and now buying PLUS only. and as @TheSmartestHouse said, the more devices you have, the better your connection you will have. One more point: devices connected to power are repeaters.