Outlook "Disconnect" error when accessing Exchange via VPN

Current Setup:

Outlook 2003 client on Windows XP Pro SP2 box at the users house.
Exchange Server 2003 on Serer 2000 Server at the office.
SonicWall SOHO3 box at each location with constant Site-to-Site VPN connection.

I have set up the user to connect to the Exchange server with his Outlook client. He is in Cached Exchange Mode.  This setup worked fine for about 2 months.  About 2 weeks ago Outlook started showing the status of "Disconnected" and would not update any folders, even when he would do a Send/Receive. He has the same exact setup (Outlook 2003, Win XP Pro SP2) on his laptop as well.  Sometimes the laptop will be connected to the server, and update just fine when his main computer is giving him the "Disconnected" message, and sometimes they both cannot connect to the server and receive the "Disconnect" message.  The disconnection issue also happens randomly.  There is no rhyme or reason to it's madness, and I cannot find anything in the event viewer that would indicate a problem. Also, when he gets the "Disconnected" message, we can still ping and access shared folders on the server no problem, so it's not a problem of being able to see the server. Could it be authentication?  Should I change the network security settings in outlook to something other than "Password Authentication (NTLM)" since he is connecting via a VPN?  Hopefully someone out there can help.  Thank you!

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Is the host machine a member of your domain? If so, then the authentication settings will not play much role in this issue because the machine will be using pass through authentication.

If the connection is being used purely for email, then you could switch them over to RPC over HTTPS. That does away with the VPN requirement.

What happens if you recreate the Outlook profile?

You have checked to ensure that the user's password hasn't expired on the domain?

jonykarateAuthor Commented:
The host machine is not a member of the domain, and we have him using the VPN for security reasons. We do not allow users to access the network in any way without first connecting with the VPN.  I could create an Outlook profile, but that is a VERY time consuming activity because I would have to download all of his files again from the server and his Exchange account is about 1GB in size.  His password is set to never expire on the domain.
Unfortunately if you are going to support remote users then you have to take the impact that recreating Outlook profiles causes. Outlook issues are very difficult to diagnose and the profiles get corrupt very easily. 9 times out of 10 Outlook issues are fixed by recreating the profile.

Outlook is designed to detect the connection state, so if it cannot see the connection to the Exchange server for some reason then it will start in Disconnected mode. With the older versions of Outlook before cached mode the easy way to get round this was to set Outlook to prompt whether to work online or stay offline. You could try setting that - it is in the More Settings of the Account Settings.


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