An update to my original thread (I can't find it to put the update in it) so...
My problems started after updating to the latest patch and changing my ikea outlets to the ikea driver. I don't have the friendliest zigbee devices (like a cree light bulb) but my mesh has been strong through Wink, Smartthings and Hubitat. I quickly suspected the ikea driver. However, I spent the time trying to do the suggested troubleshoots (disconnect the cree etc.). Devices kept dropping and I was in a loop of resetting and readding all my devices.
Since I suspected the ikea driver, I finally change them back to generic zigbee outlets. I then went through re-adding things back to my zigbee network. Then crossed my fingers and waited. So far no drops. I restarted Hubitat (which a restart would produce more devices dropping). After the restart still no drops. I still want to monitor things and see if another update causes drops but so far I think I am out of the clear on this one. I have all my devices back in working order even the cree!
I don't know what is going on with the ikea driver but in my zigbee network it didn't play nice. Granted I am not at a place where I can say for sure because I still want to monitor it but I'm feeling 85% sure that was the problem.
I have a few of those Ikea Tradfri Control Outlets.
They seem to be working.
I changed the device type last week to the new Ikea device driver.
They seem to respond to commands.
I definitely acknowledge it is odd and others don't seem to be experiencing this. It could be a weird interaction in my zigbee network that resolved over time and happened to align with me changing the driver back.
Thanks for reporting though. I'm putting it out there in case others are desperate for why their network goes funky.
One last point.
It appears that it may take as long as 24 hours for a zigbee mesh to "settle down".
Even doing the "crash scene" (turning off the hub for 20 minutes), doesn't seem to completely settle down the mesh. I think that it just takes time.
As they say "the best things in life must be waited for..."
One thing I was wondering was does changing the driver in itself affect the network? Maybe I negatively affected my network by changing the drivers all at once. Maybe changing the drivers one at a time and allowing things to settle might have been better? Especially after an update and a hub restart?
So odd things I noticed. At first various devices (light bulbs, contact sensors, etc) were problematic. A bunch fell off at once. Over time re-added devices would drop again and devices that hadn't fallen off before would fall off.
After taking the cree off and trying to heal the network, the problem appeared to be with just my iris v1 devices. Despite the cree being gone, the iris 1v devices would not stay connected for long. I couldn't just re-discovery them either. Sometimes if a battery went dead or something, resetting the device and discovering as a previously joined device worked. Not this time. Previously joined devices would not be responsive. I had to remove the device and re-add them.
Getting tired of resetting them, I decided to put the ikeas back on their generic drivers without the cree and reset the hub again. Things seemed ok. I didn't have the iris devices dropping like they were before. I added the cree back and waited.
So far still wanting but glad I'm not running all over the house resetting and adding things back. All but a sensor in the attic, I haven't gotten the ladder out yet to fix it.