FAQ: 32 Zigbee direct connection device limit?

I don’t know the answer, but I’m waiting to see what @JDRoberts has to say here shortly :wink:

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Tagging @tpmanley

What? Really?! :thinking::grin:


side note: the hue bridge has a 50 bulb limit :frowning:

yup. just had this conversation not more than an hour ago. I was surprised too when i was able to add more bulbs after adding outlet even when the it was across the room.

I am really surprised that no one has seen this yet. When I searched about devices limit, only found limits on Zwave.

dang I didn’t know there’s a wait between replies.

Yea, I know about hue limit. I was so frustrated with the bulbs i actually purchased 2 starter kits over thanks giving. Just found out the issue is with ST hub. Still cant believe it though.

The HubV2 currently only supports 32 directly connected end devices. If you were to first connect 32 end devices (for example the sengled bulbs) you wouldn’t be able to connect a 33rd device until you join a router to the network. However the routers don’t count against the 32 end device limit and you can add as many routers as you want/need. Each router will support a limited number of end devices and that number will vary by model.

We tried to bump the end device limit to 64 in the 0.18 hub firmware release but there was an unrelated regression in the Zigbee firmware and so we had to revert back to the Zigbee firmware that has the 32 device limit. We would like to increase that limit in the future but unfortunately I can’t say right now when that might happen.


Thanks! :sunglasses:

And for those unfamiliar with zigbee terminology, a “router” in this context means a zigbee repeater, which is most mains powered devices including plug-in pocket sockets, in Wall relays, wired Wall switches, and most zigbee light bulbs which connect directly to the hub.

An “end device” are the other devices that don’t repeat, typically battery operated sensors.

The sengled bulbs are unusual in that they will not act as repeaters themselves. That’s just a choice that the manufacturer made. But that’s why you might run into the problem with the sengled brand but would not with a brand like Sylvania or Cree.

Also, any bulbs connected to a hue bridge would not count against this limit as they form their own mini network with the bridge.

And I don’t think there are too many people who are likely to have 32 zigbee sensors but no other zigbee devices, although it’s possible.

So every time you add a zigbee repeater to your network, you take some of the burden off of the hub and you can then add some more zigbee devices.

And I think that’s why we haven’t heard much about this limit before in the forums. It’s really the popularity of the Sengled bulbs which has brought this issue to light (pun intentional). :sunglasses::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb::bulb:


And 32 bulb emojis to boot! Love it! Now make a wish and turn off the bulbs. :sunglasses:

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Yikes. . . didn’t know about this. I would also think the proliferation of the Visonic open/close sensors will be an issue as they have been cheap enough I think people are buying by the fistful. I just did a count of Zigbee IDs in my IDE and I have 29 and the majority are battery powered. Several of the ones that are not are Sengled end points. I think I might have 3-4 routers. Looks like I may be in for a rude surprise soon. Is there any way to figure out how Zigbee capacity you have left in the hub? Not sure how I can tell which ones have a direct connection.

I suppose you could ask support to check for you. Unfortunately, smart things doesn’t give us any mapping tools.

If it’s really important to you there’s a way to do it, but you need to buy an additional device and it’s pretty technical:

I would also add that most people who are following “best practices” guidelines for laying out the network backbone are not likely to run into this issue. But that means putting two zigbee repeaters in every room. :handshake:I know a lot of people don’t do that.

Even one zigbee repeater in every room would probably be enough to avoid this problem even with sensors on every window—Unless you are also adding six or eight Sengled bulbs in every room.

So I don’t think it’s surprising that there haven’t been many reports of this previously. I honestly do think it’s the Sengled bulbs which are most likely to be involved.

Do you know if a device will prioritize going through a router if available even if the hub is also within direct connection range?

Each device selects a parent when it joins to the network. The algorithm is pretty complicated but includes factors like signal strength. So usually they end up picking the one which is physically closest (with child slots available, of course), but not always.

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fascinating! Another reason to use switches (if possible). Also glad i went with lightify.

Thats what I’m gonna do for all single switches. 3 way is a little complicated for me. Will either install lutron casetta or buy sengled hub. Apparently supports 50 bulbs.

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Thanks wish I had this info while ordering Sengled. They weren’t that popular 5 to 6 months ago.

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Anything on the Sengled hub won’t be seen by SmartThings. Not sure what the complication is with 3-way, but check out Zooz switches. They at least don’t require an add-on switch.

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Thanks. I’m probably ok then for a while if the generally prioritize strongest signal over primary connection to hub. How many devices can a router support? Tried to look this up and all I found find was theoretical max of a Zigbee network which wasn’t very helpful.

As @tpmanley already mentioned, it varies from device to device. And it’s not usually included in the product descriptions, although sometimes you can write to the manufacturer and ask. Four is a safe guess, I don’t know any that are less than four. Some go much higher but honestly it just varies.

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Thanks for this information. I saw some of your posts recommending repeaters to other users. As of now I have 1 Cree bulb and 1 Smart things outlet. I have been able to add 16(or 18 depending if the repeaters count as devices) more after adding both the repeaters for a total of 48.
Will try adding more repeaters to add last 10 remaining Sengled led’s. I know Sengled has mentioned on their site that their bulbs dont act as repeaters, I just wish i looked into the limitations on ST side before investing in these LEDs. Not a big deal as repeaters seem to solve this issue.

Thanks for all the help!

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Each time you add a new repeater, keep track of how many Sengled bulbs you can add before you hit the limit again. Then note that that model of repeater can support that many “children.”

If you come back and share that information with the community in this thread, that would be great, but in any case you’ll have a good idea about which repeaters will be most cost-effective for you. :sunglasses:

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