Desktop Central HTML 5 Viewer

Myself and a few of my coworkers are having remote control problems with the HTML5 Viewer. We have had to remote numerous times to the same machine. The viewer will not connect and displays message "Agent not Reachable" or it will go back to status of "disconnected". I have tried rebooting the client machines and the server. Neither worked, and we are still experiencing the problem. Some machines after trying to connect 7 or 8 times it will finally connect but then after a minute or 2 the session just disconnects.

This causes us a huge problem due to a large number of machines are at remote locations. Any help would be appreciated.