Lost core and audio devices

Core Machine

Zen Mini Mk 3 - 1GB

Network Details

Unifi gigabit - managed switches - all operations normally arise of this problem

Audio Devices

2 Meridian 218, 2 MS200, MS600 IPads Macs etc
No audio device is visible anymore

Library Size

1700 albums - 23000 tracks ( Zen Mini drive is 51% used)

Description of Issue

Had trouble yesterday with losing core… got it back eventually , but gone again today and through Roon is clearly connected there are no longer any audio zones selectable. Tried all sorts of usual tricks - nothing
Tidal still working through other devices including Naim Muso
There are no network issues - Zen Mini is connected and functioning but no longer accessible by Roon. Devices have all ben rebooted - no change