Control can't see MinimServer after rescan until server Ethernet unplugged/replugged

[Bard]

Hello

First, a big thank you to Simon from a new MinimServer user for the enormous amount of work he's put into creating a terrific music server!

Mine has been running on a Raspberry Pi + hard drive server for over a month now, controlled by Bubble UPnP on a tablet, and has been completely reliable with WiFi connections between the server, control and (several) renderers via a Billion 8800NL router. However, I relocated the server a few days ago and connected it to the router by Ethernet. Since then it's continued to work as it should EXCEPT that after a rescan (to include newly-added music) Bubble no longer sees MinimServer. Stopping and restarting the control point makes no difference; Kinsky running on a PC (with an Ethernet connection to the router) behaves in the same way. I can SSH into the server normally from both the tablet and PC, via both WiFi and Ethernet, so both connections are active. The only cure I've found is to unplug and then reconnect the Ethernet cable at the server; this restores normal operation instantly, every time.

Has anybody any thoughts on how to fix this, other than restoring the server to a WiFi-only connection?

(I've searched MinimServer documentation and this forum, btw, and found nothing evidently relevant. Apologies if I've missed something I should have noticed.)