Not sure if it'll help you, but I changed the setting in my control panel where server restarts were set to a default value of 24 hours to "never/custom interval." That seems to have helped me somewhat.
There may yet be something else going on, though. Not sure about others' experiences, but I don't recall a time where my server has stopped while there's someone playing, but once the server has been empty for a bit it does seem to stop even though I've set restart interval to never.