Certain edge networking devices such as application gateways may report status to a cloud-based threat management platform using a persistent network connection between the gateway and the cloud platform. Where a cloud computing platform for an edge networking device or the treat management platform imposes periodic timeouts, the threat management platform may monitor connects and disconnects for edge devices and asynchronously evaluate connection status of edge devices independently of a heartbeat or other signal through the persistent connection in order to distinguish periodic timeouts imposed by the cloud computing platform from networking devices that are compromised or malfunctioning.