That error message means that the plugin can't reach the deployment server on that address on that port. If the address is reachable and the port is open, then it could be a certificate trust issue. The MCRemote.log file and the Deployment Server log file may have an SSL related error in the logs. You will have to check the logs to confirm.

I would recommend opening a case with support and having them interpret the logs for you. The action you will have to take to fix the issue will depend on that interpretation.

I reckon you tried to start the conventional non-html5 remote control session on Android device.  Try to uninstall your remote-control plugin manually (in MS-Window's Control-Panel, etc), and then have a newer plug-in installed on your computer by initiating a remote-control session.

Hi Raymond, 

I have asked the user to reinstall remote-control plugin but issue remains. We have few users from different locations complaining about this. 

Issue was resolved by opening firewall access for port 5494. It was a weird case because we have 3 instances of MobiControl running on the same version, but only one instance was throwing this error.