After a few days on 140 and playing further. Removed the key offending S40Lite completely and rebuilt network. I am honestly through with it and will monitor the S31 to see if it stays connected. So, far so good. I honestly don't want to spend much more time on the S40 Lite at this point. I'll circle back on it in future. What I still don't understand is why it worked fine for almost a year and after the 157 upgrade, it decided to cause grief..
Focusing on new issue that that started with 140 downgrade where Chrome randomly announces ever 15 minutes.
java.lang.IllegalArgumentException: ChromeCast controller cannot load empty URL on line 236
I am going to perform an upgrade to latest and see if I can get a week of peace in.
It's been a little over a week since going through hoops. What I have done: (as a recap)
Removed offending SONOFF S40 out. I haven't bothered re-adding.
Rebuilt the Zigbee network. Seems fine without the S40.
Noticed 2 troublesome Aqara devices that appear to be defective were not pairing. Pulled them out. 1x Vibration - Threw out 1x new Aqara P1 Motion - Used @kkossev process for adding near hub and seems good so far.
Upgraded to 2.3.9.162 without issue.
Whatever went wrong after that 157 update seems to be a red herring. The old SONOFF S31's and DOGAIN's seem fine. What is weird is that I do have another S40 that flashes periodically but still seems to work through HE. I suspect the S40 range blows as others pointed out.
thanks got it to work by restoring cloud backup so it put the device back in the zigbee table. then doing the pair without 3,.0 repeaters.. but good to know your solution. usually if it drops off i know and can just power cycle it but for some reason this time,.. it dropped off for 3 days and i missed the notification so that apparently was too long.
The instructions above state to navigate to Settings > Zigbee Details then click "Rebuild Network"
I'm on a C-7, Platform 2.4.3.155. Since @kkossev 's instructions above clearly call out a C-8, after some googling around, I've concluded "Rebuild [Zigbee] Network" is not an option on a C-7. I also surmised, from this post:
that I could roughly simulate a rebuild by shutting down HE and unplugging it for 20 minutes. Hope this helps someone on a C-7.