Unfortunately that did not resolve the issue. The new version does appear to begin to start the server but ultimately returns to the start server screen after the loading image.
The architecture does not matter in this case it is related to the OS version.
Roon Server is not crashing. It is not being started at all. Your Roon app is on 2.71 build 1683 and it opens normally, but when you press Start it declines to launch the server because it believes one is already running:
[RoonServerRunner] Not attempting to start RoonServer because it appears to be running already
It is still holding a path to Roon Server inside a temporary folder that the updater created on 12 August, when the update was installed. That leftover is what it thinks is running. Thirty seconds later it gives up and shows you the disconnected screen, which is the behaviour you are describing. This is also why there is nothing in the server’s own log: nothing ever launched.
So the fix is to clear that leftover state. Please do these in order:
Quit Roon completely, using Roon then Quit Roon from the menu bar, not just closing the window.
Open Activity Monitor, which is in Applications and then Utilities. In the search box at the top right, type Roon.
If you see anything called RoonServer listed, select it, click the X button in the toolbar, and choose Force Quit. Please tell us whether anything was there.
Restart the Mac. A full restart rather than just logging out, so the temporary folders are cleared.
Open Roon from your Applications folder and press Start Roon Server.
We expect it to start this time. Your database, library and settings are untouched by all of this.
If it still will not start after that, there is one more thing to try before we go digging.
Look in the menu bar at the top right of your screen for the Roon Server icon and quit Roon Server from there. This is not the same as quitting the Roon app, and it is the only way to be sure the server process is really stopped.
Drag Roon into your Applications folder and choose Replace when asked.
Eject the disk image so the old copy cannot be opened by mistake.
Open Roon from Applications and press Start Roon Server on this Mac.
Doing it in that order matters. Last time the server was almost certainly still holding on in the background while you replaced the app, which would leave you exactly where you started.