How many Zigbee downlights at once is too many?

I have one room in my house with 15 downlights. This week I replaced them all with Zigbee dowlights from Aliexpress that I had previously confirmed work with MC’s zigbee light Edge driver.

I have been having nothing but problems. I have tried the following:

  • Control each device individual as part of a routine
  • Create a lighting group that contains all 15 devices
  • Create one mirror group that contains all 15 devices
  • Create 5 mirror groups with 3 devices each
  • Control each device manually.

Regardless of the settings, the devices are functionally unusable. If they respond to a command at all it takes anywhere from 5 to 20 seconds before they start changing, and another 5 to 10 seconds for all 15 to update. I notice that they seem to get “hung up” I may issue 3 commands in short succession with no response (e.g. change to blue, change to green, change to 2700k) and nothing will happen for 30 seconds. Then they will suddenly make all 3 changes back to back. This happens even when I’m only controlling a single light.

I have other Zigbee RGBCCT devices on the hub that are much more responsive, and back when I only had one of these downlights to test it was also much more reliable/responsive.

Am I doing something wrong or am I just running up against the limitations of Smartthings? I accept that the lights will likely never change state in perfect concert, but I need to be able to push the button that turns them on and have them reliably/consistently turn on within 5 seconds. I have already rebooted the hub and removed and re-paired the hubs multiple times in different configurations (and using different drivers) every time the behavior is the same.

I’ve made a video to demonstrate the behavior I’m seeing

Does anyone have any suggestions of further troubleshooting I could try to get these lights working, or am I just out of luck?

I’m posting this question as a separate thread to expand the audience. MC has already weighed in on the discussion here.

In your conversation with Mariano you say that you have an “Aeotec V2 hub.“ There is no such model. The first (and so far only) Aeotec version was a clone of the smartthings V3 hub. The smartthings V2 hub predated the Aeotec partnership. So what is the specific model of your hub?

Also, in that conversation, you said that your hub showed as having reached the “soft limit“ on memory for drivers. Once that happens, a lot of things become unpredictable. So it would be good to resolve that first if you can.

The device you linked to is a Tuya model, and those are often problematic because they use a lot of custom code. As a former field tech, The first thing I personally would do is connect them to a Tuya hub Instead of your SmartThings hub and see if they still have undesirable behavior. If they do, you are not likely to be able to correct it on the SmartThings platform. (It’s also possible that they are counterfeits, an ongoing problem on AliExpress. The English description certainly looks like it was cut and pasted from somebody else’s, and has several inconsistencies in it. But connecting them to a Tuya hub would probably isolate that issue.)

If they work fine with a Tuya hub, you will have a couple of different options. If they are supported in the matter bridge integration, you could try bringing them into SmartThings that way. Or you could try bringing them in through the Smart life app, although that will probably be on a scene basis, and may not have all the feature options you want. There may be some other alternatives as well. :thinking:

I realize that may seem like more work than you want to go through, but given the number of devices you have, it might be worth it.

There are certainly people who have more than 15 Zigbee bulbs connected to a SmartThings hub, but I don’t know what the current max limits are on individual scenes.

@johnconstantelo uses a lot of Zigbee kit and may have heard something. :thinking:


I appreciate your thorough reply.

I’m not sure where I got it in my head that the Aeotec hub was V2, I have the Aeotec “V3” hub.

I’m assuming this is just what it sounds like, remove drivers and devices until the “soft limit” goes away? I don’t think there is much fat there for me to trim unless routines contribute significantly to that memory usage.

It sounds like my next best option is to get a Tuya Zigbee hub and see if I can establish some more consistent behavior that way. This is what I get for trying to replicate this behavior on the cheap. I try to limit the number of Wifi smart devices on my network and figured Zigbee would have been the best protocol for this application, but it looks like, if I was right, I should have done some more work to find a more established brand.

Thank you again for your suggestions.

Agreed on all counts. :sunglasses:

Zigbee is an excellent networking protocol for smart lights, as Hue has demonstrated. But the quality of the engineering does matter, for both the hardware and the firmware.

I will understand if you don’t want to pay Hue prices. I like Innr and IKEA as budget brands, and IKEA has just released the beta for using their Dirigera hub as a Matter bridge (although only for lights at this point) which would give you another option for integrating them with SmartThings, while isolating them from any of the peculiarities of Smartthings’ own Zigbee architecture.

But I am a wheelchair user and very sensitive to issues of fire safety, so I don’t wire anything into the mains, not even downlights, that doesn’t have UL/ETL/TUA safety certifications. So take my advice with a grain of salt. Others will feel differently. :sunglasses:


Very wise advice which I (no offense) hope I never regret ignoring.

I’ll get a Tuya hub and see if I can get them operating correctly in Smart Life. It won’t be the most elegant solution but should work well enough for my purposes. I’ll report back my findings for posterity’s sake.


An update for anyone finding this thread in the future:

A standalone Tuya Zigbee hub almost completely solved the problem.

The lights control perfectly (and perfectly in sync) from the Smart Life app itself via the hub. As @JDRoberts predicted, the lights themselves don’t sync with Smartthings, but the scenes created in Smart Life do pull in to Smartthings as generic switches.

My solution for this was to make a “scene” for every conceivable condition I would like the lights to be able to achieve (e.g. warm white - 50%, color pattern, cool white 15%, etc.) and created a separate “room” in Smartthings called “scenes” where all these “switches” are located.

I then used each of these scenes within an automation in Smartthings using the typical triggers.

The lights are connected to a Zooz On/Off switch which allowed me to disable the switch’s physical relay, thereby keeping the lights constantly powered and allowing me to trigger on/off states (and other conditions) with the wall switch.

All told it’s working about as well as I could have hoped for. Thank you very much for your suggestion.