Question : vpn not responding over hughes satellite connection

I'm troubleshooting a vpn issue over a hughes satellite connection, keep getting error 721, remote server not responding. we have tried adjusting the mtu, no luck. the connection works fine over wireless, hardwire etc. from different locations. Any insights would be helpful. XP client, Windows 2000 remote access server.

Answer : vpn not responding over hughes satellite connection

Often times a VPN is not possible over a satellite connection for 2 reasons. 1) The basic design of satellite networks causes significant end to end propagation delays which  drastically degrades performance  2) the satellite connection will often not support various encryption protocols such as PPTP and IPSec. In your case a 721 error, which almost always indicates the GRE protocol is being blocked, sounds like PPTP may not be supported. In any case, see if you can enable PPTP pass-through on the connection, or verify with the service provider that they support the protocol.  You might also find the provider NAT's the address which again inhibits VPN traffic.
A couple of articles explaining some of these difficulties:
http://compnetworking.about.com/od/vpn/f/vpnandsatellite.htm
http://www.agristar.com/satellite_vpn.shtml
http://forum.ecoustics.com/bbs/messages/34579/127542.html