Domain Controller clients listing

Hi,

we have a primary Domain Controller and a secondary DC in our network.
we
had to do some maintenance on the primary DC so we stopped the
services on DC1, so all the services were owned by the secondary.

When
we rebooted the primary DC and started the DNS service, the most part
of the clients disappeared from the list of associated clients on DC1.

The DC1 client list is syncronyzed with DC2 list.

We verified some clients which are not listed and they all correctly resulted logged in the primary domain.

"repadmin /showreps" and "repadmin /replsum" doesn't show any error.

"dcdiag /v" instead shows this errors:

Error: 1753 (There are no more endpoints available from the endpoint mapper.)

An error event occurred.  EventID: 0xC000138A

The DFS Replication service encountered an error communicating with
partner DomainController3 for replication group Domain System Volume.

 ......................... DomainController1 failed test DFSREvent

Thank you in advance

Andrzej.