According to the description, it cannot be confirmed, but in most cases, NO CARRIER is sent by the called party or the network side. Generally, the network will have UE inactive timer. When there is no data within a certain time, the link will be automatically disconnected.
Currently we have 230 modules on the field and another 200 on the way. All of them doing the same.
No matter what we do, sending data or not, the behavior is the same. In the normal operation we have an open websocket connection all the time. We are sending reguraly a ping-pong, heartbeat messages and TCP keep-alive every 15 seconds.
One of the module firmware is: EC200SEUAAR01A04M16
We have other minor issues, and we have a hard time to understand and debug them. The AT command interface and URCs not always enough. Is there any other way to debug the modules behavior? On the debud UART or USB interface?
And one more thing to this 24h connection drop.
The 24h is always starts from the module startup.
If I start the module and the data call at 8:00AM, the connection drops (NO CARRIER) the next day around 8:00AM, and the next day around 8:00AM, and so on.