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We have a problem where some VPN clients are not able to access the server and receive the 721 error message. This is only occuring when the clients are using specific wireless or wired networks. I believe the host network is not allowing the standard PPTP connections. Is there another way I can open up to allow these connections safely. We are using Windows 2000 Server, ISA Server 2000, and Windows XP clients. These clients can connect in most cases.
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We have a problem where some VPN clients are not able to access the server and receive the 721 error message. This is only occuring when the clients are using specific wireless or wired networks. I believe the host network is not allowing the standard PPTP connections. Is there another way I can open up to allow these connections safely. We are using Windows 2000 Server, ISA Server 2000, and Windows XP clients. These clients can connect in most cases.

Error 721 Accessing VPN On ISA 2000

Microsoft Forefront, formerly known as Internet Security and Acceleration Server (ISA Server), is a network router, firewall, antivirus program, VPN server and web cache that runs on Windows servers. It includes identity management and protection systems, and discontinued systems for threat management and network protection, along with protection for Sharepoint and Exchange. The scope of discussions includes forward and reverse proxy, application and service publishing, virtual private networks (VPNs), outbound access rules, SSL certificates and network routing within either a single node or an highly-available array pairing.

Microsoft Forefront ISA Server

Hardware-based firewalls provide more sophisticated protection for inbound and outbound traffic than the simple Windows software firewall or the basic NAT firewalls found in routers. These devices implement techniques such as stateful packet inspection, deep packet inspection, and content filtering; and may include built-in antivirus and anti-malware protection.

Hardware Firewalls

Networking is the process of connecting computing devices, peripherals and terminals together through a system that uses wiring, cabling or radio waves that enable their users to communicate, share information and interact over distances. Often associated are issues regarding operating systems, hardware and equipment, cloud and virtual networking, protocols, architecture, storage and management.