Windows Server 2016 - DNS/AD problem

Hi all - at one point our DC froze and we had to do a restart. It installed a lot of updates and then once it got up and running again we started experiencing problems with DNS, passwords, mapped drives etc - please refer to screenshots. Its as if the communication between the desktops and the server got out of sync somehow.

Any idea what we can do please?

Thank you

Hi again i discovered that this seems to be an AD issue through event viewer:

The Security System has detected a downgrade attempt when contacting the 3-part SPN 

 ldap/JUPITERDC01.jupiter.local/jupiter.local@JUPITER.LOCAL 

 with error code "The attempted logon is invalid. This is either due to a bad username or authentication information.
 (0xc000006d)". Authentication was denied.

Any ideas??

Hmm, strange. I've never experienced this kind of issue. For a start, I would try to demote this DC, remove it from the domain, delete the computer object, add it back to the domain, and then promote it to a domain controller.

After that see if everything is working fine.

Br