Hi
Maybe this will help:
VPN Client Cannot Establish a Connection After You Install a Service Pack
IMPORTANT: This article contains information about modifying the registry.
Before you modify the registry, make sure to back it up and make sure that
you understand how to restore the registry if a problem occurs. For
information about how to back up, restore, and edit the registry, click the
following article number to view the article in the Microsoft Knowledge
Base:
256986 - Description of the Microsoft Windows Registry
SYMPTOMS
========
When you try to establish a virtual private network (VPN) connection from
your Windows XP or Windows 2000 PPTP client to your corporate network, the
connection may not work, and you may receive the following error message:
Error 721: Remote PPP peer is not responding
CAUSE
=========
This problem occurs when a Windows XP Service Pack 1 (SP1) or Windows 2000
Service Pack 3 (SP3) PPTP client tries to establish a VPN connection to a
Windows 2000 server that participates in a cluster that is using the
cluster's virtual IP address on TCP port 1723. When the server responds by
using Generic Routing Encapsulation (GRE) packets, it uses the source IP
address of the first IP address that is bound on the network adapter.
However, this address is different from the virtual IP address that is
requested by the Windows XP client. The Windows XP client drops these
response packets because they originate from a different source IP address
from the address that it tried to connect to.
RESOLUTION
========
Service Pack Information:
To resolve this problem, obtain the latest service pack for Microsoft
Windows 2000. For additional information, click the following article
number to view the article in the Microsoft Knowledge Base:
260910 How to Obtain the Latest Windows 2000 Service Pack
Hotfix Information:
A supported hotfix is now available from Microsoft, but it is only intended
to correct the problem that is described in this article. Only apply it to
systems that are experiencing this specific problem. This hotfix may
receive additional testing. Therefore, if you are not severely affected by
this problem, Microsoft recommends that you wait for the next Windows 2000
service pack that contains this hotfix.
To resolve this problem immediately, contact Microsoft Product Support
Services to obtain the hotfix. For a complete list of Microsoft Product
Support Services phone numbers and information about support costs, visit
the following Microsoft Web site:
http://support.microsoft.com/default.aspx?scid=fh;[LN];CNTACTMS
Note: In special cases, charges that are ordinarily incurred for support
calls may be canceled if a Microsoft Support Professional determines that a
specific update will resolve your problem. The usual support costs will
apply to additional support questions and issues that do not qualify for
the specific update in question.The English version of this hotfix has the
file attributes (or later) that are listed in the following table. The
dates and times for these files are listed in coordinated universal time
(UTC). When you view the file information, it is converted to local time.
To find the difference between UTC and local time, use the Time Zone tab in
the Date and Time tool in Control Panel.
Date Time Version Size File name
-------------------------------------------------------
03-Dec-2002 11:57 5.0.2195.6150 47,088 Raspptp.sys
13-Nov-2002 15:36 5.3.10.0 4,096 Spmsg.dll
13-Nov-2002 15:37 5.3.10.0 87,040 Spuninst.exe
15-Nov-2001 15:27 n/a 5,149 Empty.cat
Update Folder
Date Time Version Size File name
---------------------------------------------------
03-Dec-2002 15:20 n/a 7,409 Q810839.cat
13-Nov-2002 15:37 5.3.10.0 18,432 Spcustom.dll
13-Nov-2002 15:36 5.3.10.0 409,088 Update.exe
Note: This fix should be applied to your Windows 2000 PPTP server.
WARNING: If you use Registry Editor incorrectly, you may cause serious
problems that may require you to reinstall your operating system. Microsoft
cannot guarantee that you can solve problems that result from using
Registry Editor incorrectly. Use Registry Editor at your own risk. If you
want your PPTP client that is running Windows XP SP1 or Windows 2000 SP4 or
later to allow connections to a PPTP server that replies by using a
different IP address, follow these steps to disable PPTP address
validation:
1. Click Start, and then click Run.
2. In the Open box, type regedit, and then click OK.
3. In Registry Editor, locate the following subkey
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11C
E-BFC1-08002bE10318}\<000x>
where <000x> is the network adapter for the WAN Miniport (PPTP) driver.
4. On the Edit menu, point to New, and then click DWORD Value.
5. Type ValidateAddress, and then press ENTER. The default setting for
this value is 1 (on); therefore, by setting it to 0, you turn it off.
6. Quit Registry Editor.
7. Restart your computer.
STATUS
======
Microsoft has confirmed that this is a problem in the Microsoft products
that are listed at the beginning of this article. This problem was first
corrected in Microsoft Windows 2000 Service Pack 4.
MORE INFORMATION
==============
For additional information about how to obtain a hotfix for Windows 2000
Datacenter Server, click the article number below to view the article in
the Microsoft Knowledge Base:
265173 - The Datacenter Program and Windows 2000 Datacenter Server
Product
For additional information, click the following article number to view the
article in the Microsoft Knowledge Base:
271731 - Earlier-Version PPTP Clients Cannot Connect to a Windows 2000
Server
The information in this article applies to:
o Microsoft Windows XP Home Edition SP1
o Microsoft Windows XP Professional SP1
o Microsoft Windows XP Tablet PC Edition
o Microsoft Windows 2000 Advanced Server SP3
o Microsoft Windows 2000 Advanced Server SP2
o Microsoft Windows 2000 Advanced Server SP1
o Microsoft Windows 2000 Server SP3
o Microsoft Windows 2000 Server SP2
o Microsoft Windows 2000 Server SP1
o Microsoft Windows 2000 Professional SP3
o Microsoft Windows 2000 Professional SP2
o Microsoft Windows 2000 Professional SP1
Shilpa Sinha
This posting is provided "AS IS" with no warranties, and confers no rights.
