The agent details can be configured under Admin -> Agent Settings. If the agent is configured to scan at system startup, then upon starting up the computer, the agent will try to push the inventory data to the server. If the server is unreachable, then the agent will try to push the data every half an hour periodically until the server is reached. The agent configurations can be modified and new agents can be created by clicking Create New Agent button.
Mostly, the computer connected through VPN can access the server and have connectivity to it, but in turn, the server will be unable to communicate or even ping the workstation. In such case, the computer connected through VPN cannot be scanned using Scheduled Scan or by clicking “Scan Now” option from the workstation detail view. Enabling “scan at system startup” is the best solution for computers connecting through VPN.