Is this the first time you're ever using Remote Control in the environment? It looks like a potential network blockage. Port 5494 might be blocked. 

What are the version and build numbers of your MobiControl server and device agent?

Is your server an on-premises or cloud implementation?

Are the devices or server on a corporate closed network?

Is the remote control problem found in one particular device/device-model? Or in ALL devices or in different device models of your system?