Further questions:
Do you have any other audio endpoints? Do they work?
If the answer to either of the above questions is ‘no’, do you by any chance run your Roon Server on a Mac device? If so, has it recently been upgraded to MacOS 15.1 (Sequoia)?
If so, then you may be falling foul of the MacOs 15.1 issue with the network security settings issues. See the linked post below for a possible solution: