VPN authentication erratic and times out

[Guest]

I have Incoming Connections on my home desktop set up to accept a VPN
connection from outside my home network set up as a workgroup. This host
computer connects to the internet through an ethernet connection to a
wireless router. When I try to VPN home from my office, I sometimes can
connect right away but more and more frequently am unable to connect at all.
The progress dialog on the client computer displays a successful connection
to the home router dyndns URL, and the router successfully passes the request
onto the host computer but the process then times out with the message
"Verifying Username and Password ...". I am certain I have all appropriate
ports opened on the router firewall, and I can access the host with Remote
Desktop and RD Web Connection at all times without any problem. I have Norton
AV 2007 installed on the host and the problem exists regardless of whether I
have the Windows Internet Connection Firewall and/or the NAV firewall enabled
or disabled on the host. Any ideas on how to get past this?

On the host computer I get the following warnings in the System Section of
the Event Viewer. I have inserted some explanatory notes. I get no error
messages in the client event viewer. Thanks.

Event Type: Warning
Event Source: RemoteAccess
Event Category: None
Event ID: 20049
Date: 7/2/2007
Time: 4:26:49 PM
User: N/A
Computer: BOB
Description:
The user connected to port VPN4-1 has been disconnected because the
authentication process did not complete within the required amount of time.

For more information, see Help and Support Center at
http://go.microsoft.com/fwlink/events.asp.
---------------------------------------------------------
On occasion the same message will refer to port VPN4-0.
---------------------------------------------------------
Event Type: Warning
Event Source: RemoteAccess
Event Category: None
Event ID: 20192
Date: 7/2/2007
Time: 3:58:58 PM
User: N/A
Computer: BOB
Description:
A certificate could not be found. Connections that use the L2TP protocol
over IPSec require the installation of a machine certificate, also known as
a computer certificate. No L2TP calls will be accepted.

For more information, see Help and Support Center at
http://go.microsoft.com/fwlink/events.asp.

 

[Guest]

An interesting event just happened. While I was at the office, my wife at
home had to reset the internet connection on the wireless router. After
resetting, I was immediately able to connect to the VPN host on the computer
behind the router, but the VPN connection was lost about 3 minutes later.
Using RD, I was able to view the Event Viewer on the remote host and found
the first warning message below in the System folder -- disconnected because
the authentication process did not complete in time. Don't know if this sheds
any light on the issue or not.

 

[Robert L [MVP - Networking]]

Check if the router has new firmware. or this link may help,

VPN connection is disconnected after several minutesVPN connection is disconnected after several minutes. We have been seeing more and more cases like this one. We don’t really know the causes, ...
http://www.chicagotech.net/VPN/vpn3minutes.htm


Bob Lin, MS-MVP, MCSE & CNE
Networking, Internet, Routing, VPN Troubleshooting on http://www.ChicagoTech.net
How to Setup Windows, Network, VPN & Remote Access on http://www.HowToNetworking.com
An interesting event just happened. While I was at the office, my wife at
home had to reset the internet connection on the wireless router. After
resetting, I was immediately able to connect to the VPN host on the computer
behind the router, but the VPN connection was lost about 3 minutes later.
Using RD, I was able to view the Event Viewer on the remote host and found
the first warning message below in the System folder -- disconnected because
the authentication process did not complete in time. Don't know if this sheds
any light on the issue or not.

 

[Guest]

Have read the links and understand. However, it is not clear whether the MTU
should be changed on the VPN client or host. Can you tell me?

 

[Guest]

My router already had the latest firmware. I went ahead and followed the
procedure for changing both the PPP and VPN MTU on both the client and host
machines. No success. I do notice, however, that this problem only occurs
while I am at my office operating within the office network. If I go
somewhere else and use a connection such as WIFI at a local coffee shop, I
always seem to get a VPN connection to home. I will talk to my office IT
professional about this, but if there are any avenues of inquiry you want to
suggest, we will both welcome it. Thanks.