Ongoing scheduled backups stop after few days

I have successfully installed and used Duplicati to schedule and run daily backups on a Windows 11 PC. Files are successfully stored on Box,com storage, After working properly for several days, Scheduled backups stop. They will resume if I open Duplicati. However then they stop a few days later. I have uninstalled and reinstalled Duplicati. Same behavior. What can I do to fix?

is this PC a portable (that is, with a sleep function enabled) ? do you see some symptoms of a crash in the Windows Application log ?