After a recent upgrade to OS 5, the mobile app stopped connnecting. See attached message presented on the App.
As you may know you need to use My Cloud OS 5 Mobile app and My Cloud OS 3 Mobile app doesn’t work with OS 5 firmware.
So you need to reconfigure your cloud service, add user and then install the Mobile app.
The below KBA might help you to solve the issue.
Thanks but I did all that with the firmware migration. Had it all up and working great for a couple of months and then the cloud access stopped working.