AWS IoT Core now provides two new Amazon CloudWatch Log event types that help you troubleshoot device connectivity issues and authentication errors across your Internet of Things (IoT) fleet. The new Ping log event type is emitted when devices send MQTT Keep-alive messages, and it enables you to identify connections or devices that were unable to keep the connection alive. The new Connection.AuthNError log event type records rejected connection attempts due to authentication failure, along with detailed error codes that tell you what went wrong, so you can resolve credential and certificate is
Source: AWS What's New — read the full report at the original publisher.