Recently updated to Windows 10, version 1809, removed the Remote Server Administration Tools (RSAT) that were previously installed.  This is common with such updates, however, this time around I was unable to reinstall the tools.  After much digging, I discovered that this is because Microsoft has made the RSAT tools a part of the “Features on Demand” in Windows 10.

Features on Demand (FODs) are Windows feature packages that can be added at any time.
https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/features-on-demand-v2–capabilities

More info on Windows Features on Demand: https://searchwindowsserver.techtarget.com/definition/Microsoft-Windows-Features-on-Demand

To install RSAT on Windows 10 version 1809, open an elevated Command or PowerShell and run the following DISM command:

 

Once the install has completed you will notice the tools installed again under ‘Windows Administrative Tools’.

 

Here are links to additional info: