See the link to "EventID 1373 from source Active Directory" for information on this event.
On one case, this problem was due to the IIS Admin Service being disabled.
I had a DC with SMTP installed but disabled. Removing SMTP eliminated the errors.
I noticed that when I installed a second NIC in my server, the IP address of the server (SMTP) which is needed for this type of replication was mixed up. Checked the properties and it worked fine after that.