What the heck, device activity showed multiple zigbee devices had dropped off overnight. Looked at settings and discovered the entire zigbee network was offline.
Ok so suitably pissed (who wants to rejoin every device on a Sunday) I reboot the hub and it goes offline and doesn't reboot. Light's still blue, so I wait..... . Ok so now everything really is dead - no diagnostic tool. Which leaves me no option but to nuke the hub by pulling power.
So is there a correlation between this event and 2.2.4? I don't know but it's never happened before. (PS nothing new added to the hub during this period other than to update a couple of simple automation rules using 1.1)
This sounded like your hub crashed hence the Zigbee radio went offline. I would look in the past log to be sure your database is not corrupted otherwise it will happen again.
I've noticed a couple of times after a reboot that a hub sometimes will briefly show a Zigbee offline message. It seems to clear up though. Today at my clients on a C-7 I did a shutdown, pull plug, restart after funky z-wave inclusion and when it came back up the zigbee went offline, no devices etc - I don't HAVE any zigbee devices on that hub yet. I got it back by going to the Zigbee details page and bringing it offline then putting it back online again. This seemed to work okay. I did end up rebooting a bit later and everything was fine.
There was a bug with zigbee "last activity" timestamp getting messed up when hub time changes during a reboot. This has been fixed a few versions back, though, please let me know if you're on the latest version and it's still happening.
We also know that Zigbee radio can overheat and go offline - with any firmware version. I can take a look at a particular hub if that's what's happening.
Ah crap. Zigbee radio just went offline. Reboot did nothing so pulled the plug again. This time the C4 is refusing to boot up at all, blue light is on.
Left it unplugged for a while but still nothing. Powered up with no zwave/zigbee sticks, finally booted after a few tries. Twice in 2 weeks! @gopher.ny how can I diagnose further?