It’s too bad we couldn’t figure it out. Was hoping support would chime back in.
If you are going to the trouble of ordering a new NUC it might be worth it to just uninstall everything of your remotes and try again. Then try reinstalling ROCK on your current NUC.
Just to see if that does it? Do you have a back-up of your DB that you can restore?
I think some are getting the OS and Roon server numbers mixed up
Latest Roon server software is: