After setting the CLASSPATH environmental variable on Windows Server 2016 using the Control Panel/System/Advanced Settings/Environmental Variables UI Tool - the CLASSPATH value reverts back to its original value when the system is restarted.
We looked at other answers and this was the method they described for setting the value permanently (i.e. as opposed to setting it at the command line which isn't.)
Why is this happening? How do we ensure the new value for the environmental variable stays to the value to which we set it?