The Data Connectors will queue up events if the endpoint URL it is pointing to is not acknowledging them. The events will be resent until successfully delivered. The pause between each resend attempt will gradually increase to reduce the load on the receiving side.
Sensors do not buffer data
There is no sensor data buffered in the Cloud Connector or the sensor. The sensor needs to be within the range of a Cloud Connector, that is connected to the DT Cloud, for data to be saved and available via Studio and the API.