Is there a maximum number of devices for Sky Connect

Configuration Zigbee
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My system runs on an Intel Nuc using a Conbe II via ZHA. The Zigbee network has 64 connected devices some of which are mains powered and such as Hue bulbs and Mini Sonoff switches that act as repeaters.

It has been running in this configuration for many months using Zigbee channel 15.

I purchased a Sky connect device, migrated the Radio to it and apparently successfully, but then I started to find some devices, like temperature sensors or PIR’s were not connected and wouldn’t connect.

After a couple of days I migrated back to the Conbee II radio and the network settled down and has been working normally for a couple of weeks.

Is there any sort of limit on the number of devices that can be attached via a ZIgbee radio?

And is it possible (or advisable) to have 2 radios working side by side in one configuration?

Thanks

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Yes, but make sure the use different channels. And there can only be one ZHA running, so the other would need to use Zigbee2MQTT. And it would form 2 separate Zigbee networks.

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I’m moving from ioBroker to Home Assitant, so I have the chance for a new clean setup.

Due to the news from Philips/Signify that they want a cloud account for the local bridge in the future, I’m thinking of transferring everything directly to Sky Connect. I wonder if there is a limit off maximum devices for Sky Connect. I have about 180 Hue bulbs and 15 motion sensors (spread over 3 bridges because of the limit in the Hue Bridge).

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Theoretically, it should be possible. But I think you will have better performance if you split the network in two.

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Thanks. Split in what way? I read that you can only run one Sky connect?

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If using the Skyconnect with ZHA, indeed. If using Zigbee2MQTT, you can have multiple networks. Or one ZHA and one Zigbee2MQTT.

You can start with one network, if it performs to your satisfaction, leave it on one network.

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OK, Thanks

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Be sure to read and try to follow these tips → Zigbee networks: how to guide for avoiding interference and optimize for getting better range + coverage

The Zigbee Coordinator firmware does have a limit on the maximum number of devices that you can have connected directly to the Zigbee Coordinator (e.i. “direct children”), but you can add more many using Zigbee Router devices, so the bulk of the devices should be connected via Zigbee Router devices (e.g. most mains-powered devices and dedicated Zigbee repeater/extender products). See → https://www.home-assistant.io/integrations/zha#using-router-devices-to-add-more-devices

After that it is the performance of the EFR32MG21 chip inside the SkyConnect that will set the limit, which is about 200 Zigbee 3.0 devices or thousands of older Zigbee Home Automation devices, (the higher security of Zigbee 3.0 devices have a larger overhead/footprint).

Anyway, 64 devices and more is not a problem is as long as you have enough Zigbee Router devices.

Personally, I can recommend buying and adding a few such dedicated Zigbee Router devices as they were designed to act as a stable (always-on) backbone of a Zigbee network mesh:

  • “IKEA Tradfri Signal Repeater ” and “Aeotec Range Extender Zi ” are products that work very well out-of-the-box, while a more powerful alternative is to make yourself some semi-DIY variant by flashing the correct Zigbee Router firmware to Zigbee Coordinator USB dongles and then using them as stand-alone Zigbee Signal Repeater devices in USB-chargers for power, like, for example, either the Sonoff ZBDongle-E (EFR32MG21 based) or the Sonoff ZBDongle-P (CC2652P) work great as dedicated stand-alone Zigbee Signal Repeaters with recommended firmware.
    • Buy a few additional new Zigbee USB adapters to use after re-flashing them with Zigbee Router firmware.
      • Reflash/reuse modern Zigbee USB adapters to act as Zigbee Router devices by changing Zigbee firmware.

Search these forums for more “Zigbee signal repeater” or “Zigbee range extender” Zigbee Router tips.

You can not simply install a second instance of the ZHA integration as each Home Assistant instance currently only allows to use of a single instance of each native/embedded integration that is built into Home Assistant core, (there are ways to hack around that by manually renaming the second integration of the ZHA component code that is really only something that ZHA developers do for testing).

If already using the ZHA integration and you absolutely want second Zigbee gateway then easists is to buy and connect another CC2652P-based Zigbee Coordinator USB adapter then install the official Zigbee2MQTT Home Assistant addon as it is possible to use as the same time (just select a different Zigbee channel when installing it).

You can even install as many external instances of the stand-alone Zigbee2MQTT application as you like because that is abstracted via MQTT, so if you want then you can buy more Zigbee Coordinator adapters to use with those (one Zigbee Coordiantor adapter per Zigbee gateway instance).

But as already noted, as long as you are under a total 200 devices I would not generally recommend splitting a Zigbee network, if possible it is better to have all “production” devices on the same Zigbee network as having more Zigbee Router devices on the same Zigbee network will make it more stable will.

In my humble opionion the only good reasons why wanting to have two seperate Zigbee networks are:

  • You want to try out two different Zigbee gateway integrations, such as the ZHA integration and Zigbee2MQTT, which can sometimes a must if one or the other does not yet fully support a specific new device that you want to use, such as example ZGP (Zigbee Green Power) devices → ZHA integration support for ZGP (Zigbee Green Power) devices via zigpy?
  • You have a remote area that can not be reached due to being well out of range or shielded and you want to control Zigbee devices there using the same Home Assistant instance.
  • You want to have a seperate dedicated experimental “lab” or “test” Zigbee network to try out new devices or troubleshoot problem devices separately to not affect the “production” Zigbee network. This is at least something that most ZHA and Zigbee2MQTT developers/testers have for development and testing.

Anyway, Zigbee devices can only be connected to a single Zigbee network (and not to two networks).

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