Domain Controllers Fail to replicate

[Leavii]

Morning,

I currently have 4 DCs all at the same site but across different networks.  They can all ping each other and access each other's sysvol, but two of them, DC and DC3, will not replicate and I get this error when I try the following:

repadmin /replicate dc3 dc dc=domain,dc=com

DsReplicaSync() failed with status 8452 (0x2104):
The naming context is in the process of being removed or is not replicated from the specified server.

Nothing has changed on the network for DC and DC3, but this morning DC4 was added for a new network.  Shortly after DC and DC3 started having this problem.  Again, all DCs can ping one another and access each other's sysvols.  DC and DC3 can replicate to all other servers, just not to one another.

I have read this typically means an issue with the network connection, and I have checked everything several times and it doesn't seem to be my problem.  My next thought is to demote dc3 and stand up a new DC for that network but seems a little drastic.  DC is my PDCe.

Here is my "dcdiag /a" from DC on OneDrive: dcdiag-9.23.23.txt

[#2 · Accepted solution]

You could follow along here.     

Active Directory replication error 8452 - Windows Server | Microsoft Learn    

[#3]

@Dave Patrick 

Makes total sense.  Add a DC, topology changes.  Didn't think about that.  We have this SNMP monitor that started sending all kinds of alerts for failures so late at night I was more annoyed than anything :D. 

Also, I did see the topology changes in Sites and Services, but it didn't occur to me that they couldn't replicate to one another via repadmin so I assumed something was actually wrong.