Go to a Command prompt, type the following commands Enter after each one.
Netcfg -u MS_L2TP
Netcfg -u MS_PPTP
Netcfg -l %windir%\inf\netrast.inf -c p -i MS_PPTP
Netcfg -l %windir%\inf\netrast.inf -c p -i MS_L2TP
Another solution -
|1.||Click Start, and then type regedit in the Start Search box.|
|2.||In the search results list, right-click regedit, click Run as Administrator, and then click Continue in the User Account Control dialog box.|
|3.||Locate, and then click the following registry subkey:
|4.||Create the following registry entry under the previous subkey. If this entry already exists, edit it so that it appears as follows:Name: AllowPPTPWeakCrypto
Value type: DWORD
Value data: 1
|5.||Exit Registry Editor.|
|6.||Restart the computer.|
Another possible solution-
Under the properties of the VPN connection – go to the security tab and change the protocol to CHAP from MS-Chap v2. Set no encryption Allowed in order to change that to Chap.
We have also seen the IKE service stopped under services…restart the service.
Set the protocol to PPTP and have both MS-Chaps checked