I have a Server 2012R2 which has several symptoms related to AD access and replication. Here are some examples and some related event log descriptions:
GPMC cannot connect to the AD. DFRS replication fails - Error: 1726 (The remote procedure call failed.) SMB outbound connections sometimes fail - The Kerberos client received a KRB_AP_ERR_MODIFIED error from the target server. Knowledge Consistency Checker (KCC) was unable to form a complete spanning tree network topology. DNS - The DNS server has encountered a critical error from the Active Directory. Check that the Active Directory is functioning properly.
The server is a 2012R2 Hyper-V guest, it was hosted on a Fujitsu server 2012R2. It has been moved (VHD only) to a Dell server 2016 host, with a new vNIC and Hyper-V switch. The problems described show no change both before and after the move. The SYSVOL share seems to be normal. The Windows firewall has been disabled. SFC /SCANNOW and DISM health checks and restores have been completed.