Deixe o ISTG no valor padrão (se tiver sido alterado, altere-o de volta). Exclua todos os links manuais e deixe o KCC restabelecer sua própria topologia.
Informações adicionais aqui , particularmente ...
The Knowledge Consistency Checker (KCC) creates connection objects
automatically, but they can also be created manually. Connection
objects created by the KCC appear in the Active Directory Sites and
Services snap-in as and are considered
adequate under normal operating conditions. Connection objects created
by an administrator are manually created connection objects. A
manually created connection object is identified by the name assigned
by the administrator when it was created. When you modify an
connection object, you convert it into an
administratively modified connection object and the object appears in
the form of a GUID. The KCC does not make changes to manual or
modified connection objects.