One or more devices is unavailable. Identify which one.

[Franck93]

When I tell Google "switch on all lights" , I almost always get as an answer "one or more devices are unavailable. You might wanna try to reset them" 

All my lights light up fine though.

So how do I identify which device needs to be reset? 

Also when I specifically tell Google which room I want to switch on, it almays works fine without saying that some devices are unavailable.

I use Phillips hue for my lights and a bridge.

Is there a limit as far as the number 9f lights that can be controlled? 

[Mashroom]

No idea about Phillips Hue, but I've had a similar experience. For me it was due to previously renaming/resetting smart devices; had to check through devices' respective apps and delete old iterations. I use a combination of MirabellaGenio and Lenovo lights fyi, so probs not helpful, but maybe?