Not all lights change while switching a group

I have an conbee 2 stick (firmware 26720700) and use phoscon (2.15.03 / 21.4.2022). I paired over 50 devices. In OH3.2.0 i create a group with 18 lamps (channel brightness) to control them all. If i change the brightness over my group, some lamps did not change. I have no idea to fix it in an easy way. Has anybody an idea?

You’d have to look more closely at what goes on, but it sounds like you just flood the communications with commands. It depends on the technology whether they get queued, discarded, re-tried etc.

One workaround would be to command by rule which issues commands to individual Items with a delay before the next one.

I don’t know how i can floot the zigbee network in this way. There is an group with members an i change brightness to 50%. Some of the members (not always the same) do not change thier brightness. If i realize it with rules than i could not use the group. I should work with tags for example. Is there an other possibility?

openHAB does not communicate directly with your Zigbee devices. It communicates through your Conbee 2 controller. So when you have openHAB send 18 messages to the controller simultaneously, you’re flooding the controller. That’s probably why you’re getting this:

I suggest removing group members until you can reliably control the group with no dropped commands. That will tell you how many commands your Conbee 2 can reliably handle at once.

Once you know the controller’s limitations, you can make smaller groups and set up a rule as @rossko57 suggested: if your first group receives a command, send that command to the other groups with a delay between each one. The delay doesn’t need to be long, just long enough that the Conbee 2 can keep up. You can experiment with the delays to balance speed and reliability.

Not that I can think of (assuming that flooding is the root issue). I get that it’s not ideal to have to use a rule, but the limitation here is hardware, not software. Unless there’s a firmware that enables the Conbee 2 to handle more commands, you need to manage the limitation in openHAB with a rule/delays.

Many thanks for the answers. I will change the group size in the next week und report my observation here.

It runs with an group size of 6 members. So I have different groups and change the values with an delay of 3 seconds.

Thx for helping with this issue.