Hi
I was discussing that topic with a Symantec employee some weeks ago. You should first tweak the setting "show agents as disconnected after (time/hours)" in console advanced settings taking in consideration your needs. Less hours here, more accurate status of your agents. If you want even more "live" results concerning the connection, you should recycle all your endpoint servers, therefore only the agents really active at the moment will be showing as "connected" in the agents list.
Cheers,