All Zigbee Sengled lights suddenly stopped working and required a re-join - Random ZigBee reconfiguration?

[Hatallica]

For your consideration:

Sengled E11-G13 Bulbs keep dropping out

A search of the forums will produce perhaps a half dozen similar experiences. Some report improvement with the addition of a repeater. Others report that removing Sonoff outlets improved the situation. I am in the group that had 10 or so suddenly misbehave at once and replaced them with Innr. I am also now removing the Sonoff outlets from my system, as a precaution.