Rebooting everything (all devices) seems to have done the trick - both for me and another person with similar issues on Reddit. It has now been 24 hours since I rebooted everything and there has not...

My rebooting effort from yesterday remains successful so far today.(fingers crossed) Just in case it makes a difference, after reverting to 5.4.7 for the OC200 and 3.20.2 for the SG2210, I have not...

@Fleegle61 Did you try rebooting everything like I did?

Update #3 At the risk of jinxing myself.... At 6:30 pm (EDT) last night, I rebooted all of my Omada devices from the OC200's device screen. Everything came back up, reconnected, and readopted fine....

@Fleegle61 said "Little of a pain to do the 2210P since I had to un-adopt it first. Even though I had the file and tried to upload and upgrade, the system would not let me until I took it out of the...

@Philbert Thank you very much! That will make my transition to a replacement OC200 if my current OC200 ends up being my issue.