After upgrading our last Windows 2008 R2 Domain Controller to Windows Server 2012 R2, three of our legacy servers and computers stopped communicating with Active Directory. Basically when we wanted to logon there was the message that RPC was unavailable. After several hours investigating and troubleshooting TCP and DNS tried to re-join them to domain with no success. We could join them to a child domain that has only one Windows 2008 R2 Domain controller successfully, so that pointed that there were a change in Windows Server 2012 R2 protocols, googling it I found the answered on Windows OS Hub website!!!
It was SMB 1.0 protocol being ot enabled on Windows Server 2012 R2 and some service dependencies.
Have a great day!!!