Will the data in the LAN be automatically uploaded after being disconnected for a period of time?

Whether to upload automatically depends mainly on the software.

In other words, the software you use supports automatic uploading.

For example, we used to be a telephone voice supervision system, which can support local storage for 400 hours. In practical application, the data will not be affected if the network is disconnected for half a year, and the data will be automatically uploaded after the network is restored.