My hubitat c5 is zigbee offline. I searched for the same situation through Google search, and it said that shut down, then reboot after 30 seconds, so I did it several times. but it doesn't fix it.
At first, pan id and extender pan id appear, but immediately zigbee goes offline and changes to a null state. How can i fix it?
Try shutting down your c5, remove power for a few minutes, and try starting it up again. If it happens again though should probably look further. Sometimes if the hub becomes overloaded for some reason the zigbee radio is the first to take the hit.
I've been having thise issue for at least like 6 months on my C5, it keeps going offline like every week or 2. Reboot will fix that though.
I have not added any device for months, not major change to apps. Originally I thought something wrong with my C5 but I've seen this issue reported by others too. I can only suspect it's triggered by some firmware change before which might cause issue with some existing drivers.