DC connection issues

Hi,

We are experiencing a rather peculiar problem. We have one DC in The
Netherlands (NL) and one DC in the UK. NL and UK are connected through a VPN.

When we try to connect via RDP to the UK DC the connection is very unstable
and we do not even get the login screen, the connection is dropped. Also
opening the sysvol share fails.

When we however connect via RDP to a workstation in the UK it is very
smooth. If we then start a RDP from the UK workstation to the UK DC, the
connection is smooth also. Furthermore there is a AD replication issue.

We tried changing the MTU settings (to 1500) on the router and some registry
settings regarding the MTU size on the server without success. I think it is
strange we are able to connect via RDP to a workstation in the UK but not to
the DC.

MORE INFO:
---------------
* Both DC's are running Windows 2003 R2 SP2

* Single domain, W2003 functional level

* Two AD sites

* NETDIAG shows this error:
Default gateway test . . . . . . . : Failed

[FATAL] NO GATEWAYS ARE REACHABLE.
You have no connectivity to other network segments.
If you configured the IP protocol manually then
you need to add at least one valid gateway.

I tested the gateways and the gateways ARE reachable, so I do not understand
this error.

* DCDIAG shows this error:
Testing server: UKSite\UKDC01
Starting test: Replications
......................... UKDC01 passed test Replications
Starting test: NCSecDesc
......................... UKDC01 passed test NCSecDesc
Starting test: NetLogons
......................... UKDC01 passed test NetLogons
Starting test: Advertising
......................... UKDC01 passed test Advertising
Starting test: KnowsOfRoleHolders
[NLDC01] DsBindWithSpnEx() failed with error 1727,
The remote procedure call failed and did not execute..
Warning: NLDC01 is the Schema Owner, but is not responding to DS
RPC Bind.
[NLDC01] LDAP bind failed with error 1053,
The service did not respond to the start or control request in a
timely fashion..
Warning: NLDC01 is the Schema Owner, but is not responding to LDAP
Bind.
Warning: NLDC01 is the Domain Owner, but is not responding to DS
RPC Bind.
Warning: NLDC01 is the Domain Owner, but is not responding to LDAP
Bind.
Warning: NLDC01 is the PDC Owner, but is not responding to DS RPC
Bind.
Warning: NLDC01 is the PDC Owner, but is not responding to LDAP Bind.
Warning: NLDC01 is the Rid Owner, but is not responding to DS RPC
Bind.
Warning: NLDC01 is the Rid Owner, but is not responding to LDAP Bind.
Warning: NLDC01 is the Infrastructure Update Owner, but is not
responding to DS RPC Bind.
Warning: NLDC01 is the Infrastructure Update Owner, but is not
responding to LDAP Bind.
......................... UKDC01 failed test KnowsOfRoleHolders
Starting test: RidManager
......................... UKDC01 failed test RidManager

* modifying the registry settings "Server2003NegotiateDisable",
"EnablePMTUBHDetect", "EnablePMTUDiscovery" and "MTU size for the network
interface" did not fix the problem

* kb899148 is not applicable, the servers are at SP2

I really have no clue where to go/look next :-(
--
Regards,

Erik
MCSE 2000/2003