ROCK stops displaying all Sonos Zones

There are a number of switches involved

Two of the Sonos are connected to AMS-2600 (unmanaged).
One of the Sonos is connected to AMS-2624P – this is a managed switch – but it is NOT using the 16 POE ports for the Sonos.

I lose two of the Sonos, so at least one would be on the unmanaged switch.

The NUC connects to AGS1008 (unmanaged) then to one of the AMS-2600 switches.