Why Your IoT Device State Is Probably Wrong

You built the connected device platform. The dashboard shows device status in real time. Your customers are happy — until a door that the system says is locked is standing open, or a sensor that shows "online" has been offline for six minutes. The data was never missing. The events all arrived. The problem is subtler than that: your system resolved the wrong state from correct inputs. This happens to almost every IoT platform at scale, and it almost always comes down to one of three unhandled edge cases. The Late-Arriving Disconnect Here is the scenario. A device drops its connection briefly — 800 milliseconds — then reconnects. Your broker receives two events: T+0ms → RECONNECT (arrives first, processed first) T+340ms → DISCONNECT (late-arriving, processed second) Network variance inverted the delivery order. Your system processes them in arrival order, so the final state is offline . The device is online. Your customer gets an alert. This is not a bug in your broker. It is a design g