“Windows VPN Client Error”

A private VPN using Windows standard client is simple and reliable, but sometimes can have problems. These may be difficult to identify and rectify.
The first thing to do is identify the error. This may be found in the Windows System Application log files.
Open the Event Viewer
Press Win + R - to open the Run command dialog box.
Type eventvwr - press Enter to open the Event Viewer.
Highlight Windows Logs/Application/Filter - This will bring up the Filter box.
From Event Sources drop down list select RasClient - Then tick Critical ,Error and Press OK.

1.If the log shows Ras Client Error “The error code returned on failure is 720.”
Then try Scenario 1: as below.

Scenario 1: Reinstall WAN Miniport (IP) interface drivers

Reinstall the WAN Miniport (IP) interface driver:

1. Open Device Manager.
2. Right-click all the network adapters whose name starts as "WAN Miniport," and then select Uninstall device. Here are some adapters that you may observe:
   • WAN Miniport (IP)
   • WAN Miniport (IPv6)
   • WAN Miniport (GRE)
   • WAN Miniport (L2TP)
   • WAN Miniport (Network Monitor)
   • WAN Miniport (PPPOE)
   • WAN Miniport (PPTP)
   • WAN Miniport (SSTP)
3. On the Device Manager menu bar, select Action > Scan for hardware changes. This will automatically reinstall your WAN Miniport devices.
4. Run the VPN client connection again and it should connect.