Roon can't communicate with Linn DS

Roon Core Machine

Qnap TS453A

Networking Gear & Setup Details

Packedge Router RK1 and Netgear switch

Connected Audio Devices

Linn Selekt DSM Bluesound powernode Sonos Bridge

Number of Tracks in Library

5700 Tracks

Description of Issue

The linn Selekt DSM isn’t visible in the audio setup via linn streaming.
However it is visible via airplay. Other roon devices are working correctly. So than I looked for the subnet for linn streaming as suggested in another post. It was not visible either. This setup had been working correctly for several months.
Any suggestions

@John_Sanders2 - Have a look here: