Replication Errors with 2008 R2

Hi Experts!

We owned a 2008 R2 multi-site single domain and we are currently facing problems with replication. We also have an IPSEC tunnel above WAN which divides the places of the entire divided subsets. In the mid position, we have DC1 & DC2 domain controllers and they are able to replicate very well. When I build StoreDC1, it was made in the central position and was replicating very well. As soon as it was shifted to site, forwarders were modified properly and the Secondary DNS is setup to DC1 and DNS on two ends that results to a new and appropriate IP addresses. I was unsure if there is an outbound replication but I there has been some inbound replication.

For the past months, the issue seems to incur with the quantity of time that the IPSEC tunnel was down when the servers can connect with each other. I encountered a problem when browsing UNC from StoreDC1 up to DC1. I always received a login failure error. The error is also stating that the target account name is incorrect. The errors that I am facing when running the Repadmin /replsummary from DC1 domain. But the rest of the replication partners have no issues. The error states "experienced the following operational errors trying to retrieve replication information: 8341 – DC1.Domain.local 8341 – DC2.Domain.local". I received the same issue in DC1 and DtoreDC when running Repadmin /showrepl. The error "The target principal name is incorrect" as well as "***WARNING: KCC could not add this REPLICA LINK due to error" appears.