My server has dropped the mapped network I have set. It has happened at least twice. I am thinking it is a windows issue but not 100% on that.
What do you mean your server dropped the mapped network? Do you mean the mapped drives are no longer listed in Plex or Plex just cannot access them?
If the latter, it could be because PMS checks for the drives when it starts. If those drives are not available at the time it does it's check, they are then treated as unavailable. You can just close and restart PMS and the drives will be seen again.