Yes, I’ve done that several times, all to no avail. I should say that this occurred after I updated to the latest Beta of 15.5 The Local Network pane also shows two instances of Roon Server that are linked (turning one off also turns the other one off, and vice versa)
Here’s the screenshot. When quit the server and start the Roon app, I’m asked to sign in and then told that I’m already signed in. When Roon and Roon Server were quit there were no Roon processes in Activity Monitor. FWIW, on iOS Roon ARC tells me that the server is online, but there’s an issue that the Roon App will help with; the Roon App just says ‘Waiting for server’
Unfortunately, none of those suggestions helped. I was able to get back up and running by signing out everywhere I could and signing back in again. That seems to have solved all my problems.