@verdantaudio that’s strange. I’ve been using Mac Mini in my system since 2008. First one died after 11 years of pretty much non stop service. The 2018 version is still going strong and is being used only as Roon core.
Granted, the Mini isn’t an awesome streamer by any stretch of imagination but it’s totally fine as a Roon core.
I never ran into network problems with it. Other issues like Mac OS upgrade induced Roon bugs yes, could be annoying.
What you’re describing sounds like some sort of a firewall and or compatibility problem with ISP, DACs etc