This object reports how often, in seconds, this remote-access session sends heartbeat keepalive messages to detect whether the tunnel is still alive, with a value of 0 specifically meaning this session is not using heartbeats at all. It matters for understanding how quickly a dead session, one where the far end vanished without a clean teardown such as a client's laptop losing power, will actually be detected and cleaned up by the device; a session with a long heartbeat interval, or none at all, can linger in the session table long after the client is genuinely gone. A session reporting a heartbeat interval of 0 would explain why it might sit in the active session count long after the actual remote client has disappeared, since nothing is actively checking whether it is still reachable.