Netdom verify fails in one direction, but succeeds in the other

Hi all;
I have a scenario where we have a domain controller and a member
server in a remote site, connected by a satellite link. The DC in the remote
site can verify the member server no problem, however no DC or member server
anywhere else can verify it (Member servers say "The RPC server is
unavailable" DC's say "Access is denied").

The strange thing is however that the DC and the server at the remote
site can happily verify any other server.

This is causing centralised Apps such as SMS to fail to connect. Does
anybody have any clues or workarounds?

Thanks in advance and will summarise.