Thanks for writing in and sharing your report, and welcome to the community!
In order to better help you, we’ll need more information around your local network setup and how your Roon Server machine is connected to your router/network?
Can you please navigate to macOS System Settings > Privacy & Security > Local Network , and make sure Roon is allowed. If it is already enabled, toggle it off and on again. Then reboot your Mac, and see if the same issue persists.
Lastly, if you haven’t yet, please set up a direct hardwire connection from your Mac to your router, and see if you run into the same issues. If you do, let’s refresh your Roon instance on the Mac (Not Roon Server) -