I converted to C8 several months ago and the transition worked great. System has been working and responsive.
All of a sudden, overnight I lost my Zigbee Mesh. Only 26 of my 60 Zigbee devices are responding. The radio appears to be working, but all of the devices have lost their routing/neighbor tables.
I have rebooted, unpluged, rebuilt multiple times. I have reverted to a previous firmware and restored a previous backup. Nothing seems to work. Here is some data. Please help.
Um .. did you lose a repeater ?
Can you go and make sure all devices work manually ?
Also .. may need to update to latest firm and then do a soft reset and restore.
Do you have Hub protect ? Can you do a cloud backup ?
Devices do not work from the device page. But they do work manually at the switch.
Yes, I have Hub protect and cloud backup.
I will try a soft reset.
I did think about a lost repeater and thought that a power off + rebuild would allow the mesh to reset. But nothing came back. No neighbors present.
I fond you have to power down for 30min or more ..
this makes everyone / ZigBee freak out and try and re-find a way back to the hub,
Yea, I did a long term power down and waited days for healing. No progress.
I guess then try and do a soft reset and restore ¯\(ツ)/¯
Could try and add a few NEW repeaters .. maybe they will the new ones and connect ?
Also ..
Need to check your WIFI settings and zigbee channel.
setup hub zigbee to channel 20 with 8-12 power. < power down hub.
set your WIFI to channel ( 1 ) and reboot router.
once you have that setup .. power up hub,
I would not expect that to fix this.
A soft reset probably wont do anything useful either, you already did a backup restore which does a reset in the process.
First I would check all of your mains powered devices. Any not working, reset the device and pair it again. It will drop right into the same device that it was connected to before.
See if that brings them back working. If that works, you may need to do that with every device that is not connecting.
Did a soft reset, restore, power off for 1hr and let it heal fir 12hrs. No joy.
I will try to rejoin devices tomorrow.
I tried 4 different devices; Hue motion sensor, GE Embrighten Switches and Sengled Plugs. No Joy, nothing will re-pair. @support_team please help!
Do you see any entries in your Hub Events logs reporting your Zigbee radio going offline, possibly repeatedly?
You can try the Rebuild Network option on the Settings>Zigbee Details page. Based on issues that came up w/Zigbee when the C8 first came out, I'd suggest after the rebuild, 1. Reboot the hub, and then also 2. Reboot the Zigbee radio.
Did you check your network settings ?
setup hub zigbee to channel 20 with 8-12 power. < power down hub.
set your WIFI to channel ( 1 ) and reboot router.
once you have that setup .. power up hub,
Nothing in the Hub Logs. All the zigbee radio events are related to my reboots and updates.
I did perform a *.138 update the night before everything dropped out. But I tried reverting back to *.133 with no effect. Currently using *.139.
I performed the routine suggested above last night. This morning still no change.
Using the Zigbee Map v2.0.0, it only shows 26 of the 60 devices connected, and interview fails on all of them. I also noted that the zigbee channel scanner does not work. All zeros after many multiple attempts.
Channel scanner can show odd/empty results in some cases so that's not too odd.
Only other thing I can think of is to shut down the hub and swap the antennas (they both do Zigbee and Z-Wave) and then restart. Likely won't help, since clearly your Zigbee radio is working for the devices that are still connected, functioning. But at least you can ensure both antennas are securely fastened. 
Probably should submit a Warranty case...I'd also suggest you PM your hub UID to @support_team so they can take a look at your engineering logs.
Oh - and try to reset/re-join some of your ZIgbee devices again, now that you've done the Zigbee radio rebuild/reboot steps. Does that work now?
@danabw
I have a thought... I have my old C7 that I used before migrating to the C8 Pro. Can I simply shut down the C8 and boot up the C7? Should that work to test the zigbee mesh itself?
Each hub creates its own Zigbee mesh, so it's not going to tell you anything about the C8 by turning on the C7.
Good news... I swapped the antennas as suggested and now the mesh is starting to heal and I have successfully paired a few devices that would not pair before.
What does this say about my hub? Should I ask for a warranty replacement?
The antenna that was on your Zigbee radio is now on your Z-wave, and is possibly broken.
Or if both radios work fine now maybe it was just not seated all the way.
Watch your Z-wave and if goes downhill put in a warranty request for new antennas.
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