Disable Defender firewall for Domain in a network server 2019 Essentials GREYED OUT

You can turn off the firewall in most Windows environments using control panel. If you have a server or PC joining a domain then you may find the domain firewall settings are greyed out so you cannot turn the domian firewall on and off.

Group Policy update and all the other methods we tried do not work.

The method below does. Change it to 4 to stop the service loading and 2 to allow it to load.

Use regedit.exe and navigate to the correct setting

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\mpssvc

In there you will find a DWORD of Start. Cnage the setting from 2 to 4

This will stop the service from starting. Then re-boot.

For a bit more background read this. The answer is at the end: https://social.technet.microsoft.com/Forums/windows/en-US/695b8f43-5628-4113-b1b2-d595c758d1a4/how-to-stop-windows-defender-firewall-service-mpssvc-on-windows-server-2019?forum=ws2019