Are you able to see any errors in your Device Connection Log? You can view it by clicking on a Device in the Device List as if you were going to update the Device’s Attributes or Tags, and on the right side of the screen, there is a panel where you can click the bug icon (similar to the debug icon in the Workflow Engine).
Here, when a device is disconnected or timed out, this will be the place to gather more in-depth information about the error.
Also, the device that is reporting its state to Losant, did you write the firmware for it? How is the device communicating data, via MQTT or HTTP? Could you give me more information on the Device that you are using and the environment it is in?
Any screenshots or other information you can provide will help me understand your problem better!