Hi @Stephen_Judge,
Thank you for your post and for your patience. We’ve merged your more recent posts in another user’s thread to a single place where we can troubleshoot as needed.
ARC has multiple fail safes to accommodate fluctuations in connectivity during expected driving scenarios. These should prevent most symptoms except artwork loss (albums might appear as grey squares) and the occasional long loading time in between tracks. Even if you lose sight of the RoonServer machine intermittently - whilst having zero bars in a tunnel, for instance - ARC ought to recover.
So, something else has been at play here.
Reviewing diagnostics from the period during which connectivity was failing for you, the most likely culprit appears to be an upstream connectivity issue between your RoonServer machine and the internet.
You’re correct that we’re familiar with problems affecting standard kit, but we do need to know what kit you’re using in order to diagnose what’s wrong. Your Core is on MacOS (an iMac, I assume?), but are you using a hardwire ethernet connection, or WiFi connection, to reach the internet? If the latter, try an ethernet connection instead, as it’s likely to relieve these problems.
Do you have any network hardware other than your main router in your setup? What about network switches, mesh nodes, or access points?
Another tip we recommend to help with upstream connectivity - try entering your router’s web administration page and changing the DNS server assignment to Google DNS. Roon ARC relies on more than just your RoonServer and the phone - it also needs to call a wide number of external internet addresses to function (such as Roon’s own servers). This step should help resolve those addresses more efficiently to speed up your response time.
We await your response and we’re here to help further. Thank you!