Samsung digital signage displays have internal storage. Once the screen has received content from Wondersign, the screen will store the content and continue displaying it so the screen is never dark.
Check your internet connection and make sure that it is working properly. Unplug the power cord from the display and plug back in. The screen will automatically connect to the internet (as long as it is working properly) and check with Wondersign for any updates. Also you need to log out of your Wondersign account and then log back in.
If still not showing connected on your device manager, make sure your wifi settings are correct or that your ethernet cable didn't become unplugged.