Hi, I am not sure if this particular user fixed this problem. I have the same problem. ARC asks to log in every few days always while on cellular data. The last time it asked me to log in again I was away from home. I choose not to log in and when I was back home and connected to the wifi with my phone it connected to ARC without asking for a log in.
Error message from the ARC app on iphone:
Your Roon Core is online but there’s an issue that’s preventing access. Go to the Roon app for more information