Windows Software Update Services provides a way for Windows sysadmins to control the distribution of updates to windows computers. It also helps to save a lot of bandwidth if you don’t have a superfast internet connection.
Unfortunately many think that it is easy to setup and maintain. On newer version of Windows Server it is easy to setup but it needs a lot of care and feeding.
I you want to run WSUS you will have to run the “Server Cleanup Wizard” at least once a month, or run Invoke-WSUSCleanup in a scheduled task. If you don’t lots of frustration awaits after a few months.
If you didn’t do any maintenance on WSUS for a long time this microsoft support article will be useful. Good luck! https://support.microsoft.com/en-us/help/4490644/complete-guide-to-microsoft-wsus-and-configuration-manager-sup-maint