First, the reason analysis:
1, 721 error is due to your computer in the intranet, because there are many computers in the LAN, the server can not correctly determine which computer is, so the connection will be prompted error 721.
2, Win2003 Routing and Remote Access to build a VPN, some local dialing prompts error 721, the VPN policy changed from PPTP to L2TP after the resolution.
3. The router prohibits PPTP connections.
Ii. Solutions:
1, click "Start-run", type "regedit" command, click "OK";
2. In Registry Editor, locate the following registry entry hkey_local_machine/system/currentcontrolset/control/class/{ 4D36E972-E325-11CE-BFC1-08002BE10318};
Where is the network adapter for the WAN Miniport (PPTP) driver.
Note: "000x" represents the following 0001-0009 several options, the general PPTP is 0003, specific to one click View.
3, click the menu bar "edit-new--dword value";
4, Input validateaddress command to press ENTER. The default setting for this value is "1" (open), so it needs to be set to "0" to turn it off;
5, restart the computer.