I have a SmartThings v2 hub with ~100 devices spread around the house, which are a mix of Zigbee, Zwave, WiFi/cloud integrations and virtual switches. Of these, around 60 are Zigbee devices - approx 20 battery powered sensors, 8 smart plugs and the rest are mains powered bulbs/dimmers.
Overall, the system performs well and is responsive, with no noticeable delays in normal use. But there is one exception; I have a set of 19 outside lights (coloured Osram and EGlo smart GU10s) which are controlled using scenes, (e.g. “Set lights 1-12 to green 100%, set lights 11-19 to cool white 30%”). When these scenes are called, the lights are slow to respond (up to a minute before they have all changed) and the rest of my devices are unresponsive during that time. For example, if the 19-light scene is being activated, and then I walk into a room, the (different) motion sensor and light won’t react at all for ~60 seconds. Sometimes, one or two of the outside lights don’t respond to a scene at all and it has to be activated again.
I assume my problem is being caused by a flood of simultaneous messages to the 19 bulbs when the scene is activated, clogging up the Zigbee network. Presumably this network traffic has to clear before my other sensors and devices start responding again. I assume lack of repeaters aren’t a problem - hopefully the bulbs should be repeaters themselves, but even if they’re not I have 5 smart plugs within range as well as the hub. Being coloured bulbs may not help either, if SmartThings is sending several commands separately (e.g. "turn on, set RGB to green, set brightness 100%) - that could lead to ~50 messages sent during each scene. The bulbs are inside metal spotlight housings, which doesn’t help signal either, but they work OK individually.
Is there anything I can do to improve the response times of these bulbs, or am I hitting the limitations of the Zigbee protocol?
As adding repeaters doesn’t seem to help, is my hub the bottleneck? Would a newer hub, or even multiple hubs help?
Last resort is to replace 12 of the bulbs with a couple of Zigbee dimmers driving “dumb” bulbs, reducing the number of devices significantly, but then I’d lose control of colour.
Thanks for any advice