Hey @Christian_Frankel,
Thanks for writing in!
The first thing to examine would be the firewall on your troublesome Mac device:
Do you have any third-party security software installed on the Mac? If so, here is some additional information:
Please follow the steps in Adding Application Exception to McAfee Firewall to add Roon as an exception to the firewall.
Additionally, you can try changing the router’s listing to a Home network in McAfee: Mcafee Firewall settings for Roon 1.7 - #7 by Anthony_Lombardo
A third solution is to change the security level of Roon and RAATServer: SB3 won't connect to Roon Sever with McAFee turned on - #9 by Jeff_Barham
Lastly, I would also test out manually downloading and installing the latest update from our site directly:
Let me know how the above goes. Thanks! 