If The system cannot contact a domain controller to service the authentication request when connecting to a server, here are working fixes!

"After installing KB4586781 on domain controllers (DCs) and read-only domain controllers (RODCs) in your environment, you might encounter Kerberos authentication issues," Microsoft explains.

Microsoft has fixed a known issue causing NTLM authentication failures and domain controller reboots after installing last month's Windows Server security updates. According to a Windows health ...