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VPN connection issues post Windows XP SP2 upgrade

Our clients have two Cisco routers connected to the Internet and we configured them to allow PPTP-VPN access from our client's home. These configurations worked well with Windows 2000 and Windows XP SP1 PCs, but since we upgraded our clients PCs to Windows XP SP2, none of them can establish PPTP-VPN connections to the routers. We have done many tests, including deactivating the PC's firewall, but Windows XP SP2 PCs still fail to connect. What can I do to solve this problem?
I would verify your VPN settings on the routers to ensure that you are using ms-chap for your ppp authentication and that you have configured the ppp encrypt mppe command with the correct level of encryption (auto, 40bit or 128bit). For more information about configuring IOS based VPNs click here.

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This was first published in May 2006

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