Our VPN does not work suddenly. Error 691

Suddenly we are unable to access VPN from our server.  We thought it may be due to the network card but after replacing, the same problem occurs.  Error 691 that has to do with username and password not authenicated.  We tried new username and passwords but same message appears.

We have not changed anything settings.

The ISP confirms the designated IP can be pinged.

We setup another laptop to see if we could VPN into this.  It works based on the same IP.  We are able to access.

What could have changed on our server settings?

What can we do?
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Rob WilliamsConnect With a Mentor Commented:
The Cisco or any router can block access. If you are getting a 691 error, and you think it is due to the Cisco it probably indicates GRE is blocked. Port 1723 must be forwarded correctly or you would have received an 800 error.
Rob WilliamsCommented:
If it works with another laptop the issue should not be server related, but rather the client.
On the problematic laptop (connecting PC) check the VPN client by right clicking on the VPN adapter under network connections, and then options, and verify "include windows logon domain" is not checked, and also under the security tab, make sure "require secure password" is selected.

Another thought is to try using a different user account. Perhaps the user's account does not have permission to connect.
nuiphaoAuthor Commented:
I should have mentioned that the problem machine is the server in which the routing access has been configured.  The laptop for testing had server 2003 installed.  Anyway I have since learned it may be due to the cisco router.

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