Admin portal version 1.25 or higher
Quick navigation: Data management > Device > Select Device > General Information tab
The device is unavailable and if checking the event logs shows that it hasn't been connected for some time, and if you look at the device information in the admin portal, it should have information on Status, OS, Application version, etc like in the below image, but all those fields are blank.
Verify that the device has a working network connection, then simply click on the "Detach Device" button. The ShopFloorInterface will then reattach itself shortly.