Steam has built-in settings that can inadvertently halt downloads if you are doing other things on your PC.
Schedule conflicts: Ensure "Only auto-update games between" is turned off so Steam doesn't stop downloads during certain hours. Repair the Library Folder download keeps stopping steam
Open Task Manager (Ctrl+Shift+Esc) and look at the "Disk" column. If it is at 100%, your hard drive cannot keep up with the download speed. This is common with older HDDs. In this case, limiting your download speed in Steam settings can actually prevent the "stopping" by giving your drive time to catch up. Refresh the Steam Files (The "Soft" Reinstall) Steam has built-in settings that can inadvertently halt
Game interruptions: Uncheck "Pause downloads while gameplay is in progress" if you want to update games while playing an offline title. If it is at 100%, your hard drive