My hub has been stable for nearly a year now, that is until yesterday, when I experienced a brownout then a blackout shortly thereafter. My hub is on UPS so it never went down. Within a minute or so power was restored, that's when a multitude of problems reared it's head. I started noticing long delays on automations. That's when I started seeing the zigbee radio toggling on/off. I also got a message through the Hubitat UI that the hub was under heavy load. I rebooted the hub thinking that would restore stability, but that didn't work. Several of my plugged in repeater/outlets could not be controlled, even after unplugging and plugging back in. I then tried adding a zigbee device figuring it would restore operation. The pairing did see and re-add the existing device but I still couldn't get control. I figured I would just leave everything alone for a few hours hoping things smoothed out, but no luck. I ended up having to delete the devices from the hub and go through creating a new device. It took me hours to get things back to normal. The hub load returned to normal but the zigbee radio was still doing it's off/on thing, although at a slower pace. As of now I am back to normal after 33 hours since power was restored.
I don't know all the in and outs of zigbee but every time there is a power outage problems crop up, yesterday was the worst I've experienced. I assume this is more of a zigbee protocol issue because similar problems would happen back in the SmartThings days. I just wish it was more stable when situations like this happens. I've read hundreds of posts on problems like this but there seems to be no solution, other than to have hubs with no repeaters, which I have two like that. Unfortunately that isn't a real solution either.
Your symptoms make me wonder if the Zigbee radio was busy. The only way to reset the radios is by a power cycle, not just a reboot. Do a Settings: Shutdown, then remove the power for a few seconds when the LED goes RED (or Off).
Another option is similar, but leave the hub powered off for 20 mins. This will cause all your Zigbee devices to start a search for their hub, automatically reconnecting when they find it.
I tried both of those options. The shutdown / power remove & reboot didn't make any difference that I could see. The hub was still under heavy load & radio was still off and on.
Then I powered off, removed power for about an hour and then powered back up. Hub was still warning of heavy load and the radios were still off and on. That's when I just left it that way for a few hours. The heavy load subsided but the radios were off/on but at a slower pace. The hub was performing better. That was last night and at 8AM this morning everything smoothed out. This was at least 12 hours since I had to delete and re-add the devices that just fell off. I dread power failures because I never know if I'm going to spend a few minutes or many hours trying to get things back to normal.
In my mind, you have "something" overutilizing resources.. that causes heat and causes the Zigbee radio to shut. The "something" is cycling too and during it's down phase, the Zigbee radio turns back on. Not enough time later, the "something" goes back to up phase, over heat, Zigbee shut. Perhaps the down phase is not long enough for the devices to rejoin before the up phase shuts it all down again.
I agree something is/was using up the hub's resources. I checked the Device Stats and App Stats but didn't see anything that jumped out as being unusual. I suspect that one or more of the devices that lost power was flooding the zigbee network but without more diagnostic tools I'm just guessing. I have about a half dozen of the Centralite cube outlets and about the same with Sengled along with a hodgepodge of battery powered devices. At the time I did look at Hub Information Driver and it said the hub was at 131F. Looking at it now it's 107F. Since this morning the zigbee radio has off/on one time. Yesterday it was many dozens of times. Before yesterday there hadn't been a single drop for a year. It would be interesting to know what the cause was but like many others having the same problem, we're sort of in the dark.
The hub that had the problem is a C8. I have no LAN or WiFi devices that interface with the hub. 90% of my devices are zigbee and the remaining is zWave. My automations are well established and have changed very little over the past 3 years. Because zigbee shares the same radio band I know WiFi can interfere, but my entire system is on UPS and nothing was interrupted. Im in a single home and WiFi interference is next to none. Like I said, sometimes problems are minor meaning I have trouble with 1-2 devices not rejoining, but yesterday was a real doozy. The only thing that was different was a brownout for 3-5 seconds before total blackout. With so many zigbee outlets it hard to know which ones may be causing a problem. Thinking back I should have turned off the man breaker to see if the hub load resolved. Maybe next time.
