You need a switch. The Nucleus operating system does not allow for direct connection to the DSM via Ethernet. However if the DSM has a USB input, you could consider using that.
Otherwise requirements will be access to the internet via the switch.
Connect the switch to the Nucleus
Connect the DSM to the switch
Configure Roon for working to a Linn device.
thank you for your kind reply. my DSM has USB Host and USB Audio. Does it mean that I can install hard disk on Nucleus and then connect Nucleus to DSM via USB Audio? T
Yes, that should work OK. But if both devices are on your network as I would expect, that should work too. The only thing that will not work is direct connection between Nucleus and DSM via Ethernet cable.