Zigbee devices are very sensitive EMF/EMI/RMI interference and have a relatively short range, thus I highly recommend that everyone using Zigbee devices start by understanding the limitations and work around them, so suggest that you start by reading and try to follow all the tips here → Guide for Zigbee interference avoidance and network range/coverage optimization
Especially be sure to connect the Zigbee Coordinator adapter via a very long USB extension cable to a USB 2.0 port (not a USB 3.x or USB 4.x port ) and also keep it away from USB 3.x/USB 4.x devices.
Note that hidden among those tips there is also a suggestion to upgrade the Zigbee Coordinator firmware, so that is at least a specific tip if you are still using old firmware, see → ITead's "Sonoff Zigbee 3.0 USB Dongle Plus" (model "ZBDongle-P") based on Texas Instruments CC2652P +20dBm radio SoC/MCU
Those two things are best to begin with as they should resolve most issues.
If you are using Zigbee lightbulbs that act as Zigbee Router devices then be sure that they always have power. You should not have Zigbee lightbulbs connected via dumb wall-switch/cord-switch as it is a risk that someone will turn them off. Zigbee Router devices should always have power (always be available/online), otherwise any device connected to it will drop of and it will take time to reconnect (or sometimes not reconnect if that device has poorly written firmware as is known with older Aqara/Xiaomi devices).
If you are using Zigbee lightbulbs that are Zigbee Router devices connected via dumb wall-switch/cord-switch then you are really using the product wrong. Get instead some Zigbee lightbulbs that are specifically designed to be Zigbee End Devices (not Zigbee Router devices) if you absolutely need to connect them via dumb wall-switch/cord-switch.
If you need to use Zigbee lightbulbs that are Zigbee Router devices then do not connect them to dumb wall-switches/cord-switches and instead get some smart-switches or remotes to control them indirectly.
Regardless, I personally also 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.
- Buy a few additional new Zigbee USB adapters to use after re-flashing them with Zigbee Router firmware.
Search these forums for more “Zigbee signal repeater” or “Zigbee range extender” Zigbee Router tips.
@macottom 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 noted by @NathanCu 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).