Hello @Hjcw_Roefs,
If you download and install the “Roon” application on your iMac, are you able to connect to the Antipodes core and keep the connection in a stable manner? When you first open the “Roon” application on your Mac after installing to your Applications folder, it will ask if you would like to use your iMac as the Roon Core or if you would like to connect to another Roon Core. Under the “Other Roon Core” option you should see the Antipodes listed.
https://roonlabs.com/downloads.html
-John