Hi all,
Finally, thanks to DELL Software Support Team, our server is now fully operational.
The issue was missing files in folder C:\Windows\System32\CatRoot{F750E6C3-38EE-11D1-85E5-00C04FC295EE} serving drivers signatures.
The solution was to copy all the files in this folder from another Windows Server 2016 to the folder on affected server without overwrite existing files, and then reboot affected server.
Thank you all again for your help.
PS : I'm always waiting for a enterprise-class answer from Microsoft Support.......... Is my paid Software Assurance is really useful ?