Anyone ever find a solution for this? I am fairly certain that this is related to the Dongle Plus E as I had the Dongle Plus P for over a year without any drops (using ZHA for a time and Zigbee2MQTT later) as well as a Conbee II with Deconz for a couple of years before that.
But the Dongle Plus E does exactly what is mentioned in this thread even though nothing has changed (locations, routers, etc) from the Dongle Plus P or the Conbee II setup.