I have a number of Fibaro Dimmer 2 switches controlling my lights.
I want the lights to come on or go off together.
I have tried Groups and scenes and they both turn the lights on/off in random patterns - missing several in the process.
It appears the a delay is needed between each light going on/off. I created a rule machine program that indeed turns each light on individually with a .2 second delay and they all come on/off. BTW a .1 second delay was not enough.
Any suggestions as to how to make the lights go on/off together?
Have you looked at the mirror app?
No, but I have now and being a newbie don't see anything there that would help. If youdo, can you provide a direction?
Any on/off of “deck light” will be mirrored to “bedroom light”.
Can you clarify what you expect to happen? Groups won't cause one device to turn on or off in response to another; there intent is that you use the group device to manipulate the entire set of devices (while still retaining the ability to control them individually via the normal means). The Mirror solution above can help one device "follow" another if that's what you want instead.
I am looking to turn on one entity (group/scene/???) and have 7 individual lights turn on/off simultaneously.
Each light has it's own Fibaro Dimmer 2 relay.
I really appreciate any help to accomplish what I thought the purpose of groups/scenes was for.
With the Mirror Me above, make any one the primary and the other 6 replicas. Then, when you turn on the primary or turn off the primary, all the replicas will follow.
This is what Groups (of Groups and Scenes) is for, so it should work. Mirror could do something similar, though it's not really what the app was created for; as usual, there are lots of ways to reach the same goal. (Want another option? Room Lighting.)
You can do the same in Groups and Scenes by enabling the "metering" option and specifying some number of milliseconds, say, 200. This is not supposed to be necessary thanks to recent improvements with Z-Wave (and Zigbee) serial processing, though there is no harm in trying it if it works better for you. (It's not in some newer apps like Room Lighting for this reason, however.)
However, you might also want to look into why this does help on your network. It seems all the affected devices are Z-Wave. Do you have lots of S0 devices or any "chatty" devices in general? Do you have any "ghosts"? This document can help: How to Troubleshoot Z-Wave | Hubitat Documentation
That being said, the Z-Wave SDK Hubitat is using dos not have any way to do multicast, from what I've read, so you'll never get anything truly instantaneous like the goal is with Zigbee groups, for example (something both Room Lighting and Groups and Scenes groups can create). So, some "popcorning" is normal; missing commands entirely isn't.