Hi, I was asked to help with VPN connection in one company (technical details of networks/OS are at the end of post). A computer in other city has been connecting to the company's VPN network for about a year without any problems. Since Monday two weeks ago, the computer in the other city cannot connect to company's VPN. It reports 800 error. So far so good. I thought - the firewall, some other network problem, some client PC problem, a hanging connection. But no. I have tried everything I could think of. Let me summarize, why it is a mystery: 1. The client computer can connect to other VPNs with similar configurations (other companies running this VPN configuration). Thus, I thought, it cannot be a problem in client's network/computer configuration - firewall, ports, bad configuration.. 2. The Server's VPN is accessible from other networks (let's say can connect with mobile phone+laptop). Thus it is not a problem in server's network - firewall, ports, other configuration problems. 3. I restarted client, server, server's network router with no results -> it is not a problem with pending/sleeping state/connection. 4. In the client network we have tried following command "telnet <server ip> 1723". The telnet established the connection successfully -> the connection is not blocked in any place, the packets are coming thru. 5. We have put a different computer to the other town's office. This computer failed to connect as well. -> this gives at least some hint that the problem is possibly not in the client machine's configuration. 6. We have tried a packet sniffer on client and server. It seems that the first about 2 packets are exchanged, then the client keeps sending packets, but server would not receive anything. The Zyxel router in servers network is very basic and does not allow advanced logging. But this is at least some information. However, I do not know the details of VPN packets so well that I could get a useful information out of this. 7. Everybody, i.e. system admins and ISPs claim nothing has changed in their respective configurations. 8. It is not a configuration problem neither in client, nor server. Both have worked 2 weeks ago perfectly, and no configuration has changed since. Also, both computers can do VPN with other networks. Please help! This is not a problem anymore. This is a challenge that the computers put in front of us any help appreciated. Server's network: - static public address - Windows 2003 Server - LAN has DHCP and NAT - Zyxel router - configured to forward appropriate port Client's network: - Windows XP - DHCP, NAT - router and other network details not known VPN: - VPN server system used is the default VPN on Windows 2003 Server - VPN client used is the default Windows XP client in Control Panel/Network Connections/Create connection..

Hi tsp_,can you write just a little big characters ?tnx :)Can you try to move the first client in remote networkfrom that network to another and try to connect again at the same vpn server ?Edoardo Benussi - edo@mvps.org Microsoft MVP - Most Valuable Professional Management Infrastructure - Systems Administration https://mvp.support.microsoft.com/Profile/Benussi

Error 800 is a very general "cannot connect" message. If you are using PPTP, set your client to use PPTP instead of Automatic and see if you get a more specific error message.Bill

Hi Edoardo,we have tried the client/remote computer in other network. Everything works fine in that network.I have made the fonts bigger. Hope now it is fine.Stevo

Good test.Can you try to establish a vpn connectionwith l2tp instead of pptp ?ps: tnx for bigger fonts.Edoardo Benussi - Microsoft MVP Management Infrastructure - Systems Administration https://mvp.support.microsoft.com/Profile/Benussi

Hi,thanks, after switching to PPTP from Automatic, it started to work properly.Stevo