Windows Server 2016 notify administrator when user changes computer network password

You can achieve this using GPO:
How to Configure a Site, Domain, or Organizational Unit to Prevent Users from Changing Passwords Unless Prompted:
1. On AD Server Click Start, point to Administrative Tools, and then click Active Directory Users and Computers.
2. Right-click the domain or organizational unit for which you want to implement the new password change policy, and then click Properties.
3. Click the Group Policy tab.
4. Click the Group Policy object (GPO) that you want to work with, and then click Edit. If there are no existing policies listed in the Group Policy Object Links list, click New to create a new policy, type a name for the new policy, and then click Edit.
5. Expand the GPO, expand User Configuration, expand Administrative Templates, and then expand System.
6. Click Ctrl+Alt+Del Options.
7. In the right pane, double-click Remove Change Password.
8. Click Enabled, and then click OK.
9. Quit the Group Policy Object Editor snap-in, click OK, and then quit the Active Directory Users and Computers snap-in.
10. Click Start, and then click Run End user desktop or the policy will apply after log off / login.
11. Type cmd in the Open box, and then click OK.
12. At the command prompt, type the following line, and then press ENTER:
gpupdate /target:user /force
13. Type exit to close the command prompt.

This will not stop users to set password when password expires

May we know what you want to achieve exactly
You could set minimum password age just behind maximmum password age and it will prevent password change prompt