Thanks for writing in, it’s good to see you on the community again!
Can you be more specific in your connection issue? Are you able to successfully sign into your second Roon account?
Can you get a direct ethernet connection from your MU1 to your primary router, and see if you still have issues? It may be helpful to take a look at a set of Roon Server logs from the MU1 as well, if you could please use the directions found here and send over a set of logs to our File Uploader?