UPnP / DLNA randomly stops working on Raspberry Pi 2

About 8 months ago I ditched my old raspberry pi B and bought a raspberry pi 2.
I feed media from my linkstation nas to the pi via DLNA.
I never ever had any issues with this in the older pi 1.
However, for the entirety of the time of using the pi2 DLNA will randomly stop working. I haven’t established the cause but I think it is during a reboot or crash (but again - it is random).
Going into services > UPnP and toggling the setting “share my libraries” gets everything working again - until at a future point in time it will randomly stop working again.

I have tried several clean installs over the eight month period and several updates but the issue persists.

Anybody have any idea?
Anybody else seeing this behaviour?

quick search of the forums shows this . . . . which seems to be the same issue.