Hello
There should be corresponding message recorded in Event Viewer\Windows Logs\System every time the machine reboot.
If there is error message (it may be event id 41) recorded when the issue occurred, it means there is something wrong with the hardware and if there is no bugcheck (bsod) occurred at the same time. We may check the power issue. Or we may consider to contact the device manufacturer support.
If there is information recorded, there is may be automatic task trigger this issue.