I have a main AD root server in an HQ office. I have had 6 Domain Controllers in WAN sites for over a year. Friday the AD Server just decided to stop replicating with one of those AD servers on a WAN link.
Nothing on the WAN link has changed. We use Notes, users at the WAN site can receive Mail but they cannot send it, and that server can no longer replicate and receive the AD directory updates. The KCC Fails due to and RPC error.
Now the other 5 DC's work just fine. All of hte setup in the Sites and Services are the same, they haven't changed. We are very Hub and Spoke so all DC's come directly to the ROOT server. We will change that when we implement our MPLS network but for now they all talk directly to the ROOT.
I even tried to have the STL DC talk to one of the other DC's but they won't replicate together.
I am sure somebody has seen something similar to this in the past, at least I hope so.