Newly installed Symantec Endpoint Security agents connect up to the cloud and appear in the console, but after a few minutes they appear to disconnect.
They may occasionally appear to be connected, but only for a couple of minutes at a time.
Release : 14.3 RU6
This is often caused by a proxy timeout.
The agent must be able to connect to the SPOC (Single Point of Contact) service. This is a service that triggers a check-in action from the agent.
The agent polls the SPOC service on an interval (starting at 2 minutes) and, when served a response to pull content, the agent initiates the appropriate connection to pull that content.
If the client is unable to maintain the SPOC connection, it appears disconnected.
Adjust the proxy timeout to 5 minutes or greater, to allow the client to maintain the SPOC connection.