How to Solve Error 720: A Connection to the Remote Computer Could not be Established.

It can be fixed by uninstalling/reinstalling mini ports or resetting TCP IP Protocol.

Run Command prompt as Administrator and type the following command then hit enter

Reboot your system and connect VPN again.

If the problem persists then move on to uninstalling/reinstalling mini ports

Solution 4: uninstalling/reinstalling mini ports

First, create a restore point:
To create a restore point on Windows 7:

• Open System by clicking the Start button, right-clicking Computer, and then clicking Properties.
• In the left pane, click System protection. If you’re prompted for an administrator password or confirmation, type the password or provide confirmation.
• Click the System Protection tab, and then click Create.
• In the System Protection dialog box, type a description, and then click Create.

http://windows.microsoft.com/en-GB/windows7/create-a-restore-point

To create a restore point on Windows 8:

a) Press Windows key + F, type “Create restore” in the search box
b) Click on the settings tile
c) From the System Protection tab, click on “Create?” and follow the process to create “Restore Point”

Next step: Uninstall the non-working miniports

When doing this, make a note of the miniports that you are removing, you’ll need to know this later when reinstalling.

Removing the Problematic WAN Miniport Driver

1. Press the start button then right-click My Computer > Properties. (Windows 8 users, right-click on the Bottom left side of the screen and select Device Manager)
2. From properties go to Device Manager; if you are using an older version of Windows you will need to click on the hardware tab to get to Device Manager.
3. On the Device Manager toolbar click on View and then click on Show hidden devices from the menu list.

So, to remove each non-working miniport, do the following:

1- Right-click on the non-working miniport, choose “Update Driver”.
2- Choose “Browse my computer”.
3- In the next window, choose “Let me pick driver from a list”.
4- Uncheck “Show compatible hardware”. From the “Manufacturer” list, choose “Microsoft”, and from the “Network Adapter” list, choose “MAC Bridge Miniport”. (It can be any device the user is allowed to uninstall.)
5- Back in the device manager, delete the device that just turned into the “MAC Bridge Miniport” device.
6- Once done removing the bad miniports, reboot.

Reinstall the miniports
You’ll need to do a few extra steps, as the miniport drivers aren’t meant to be installed by users and are not visible. To avoid editing .inf files (which in a lot of cases are protected and not easily editable), we’ll do it the long way.

Download devcon.exe and extract it on your C: drive root
Go to command prompt, go to the directory C:devconi386 for 32 bit and C:devconia64 for 64bit
For each miniport that you have previously uninstalled, execute the command outlined below. DO NOT run all of them or run the command twice, as that will create a second version of the existing miniport, which can cause problems again.

If running the command reports “driver install” failure, don’t pay much attention to it, it usually does. The only problem is when it complains about the inf file missing, or a missing class (in which case you most likely made a typo in the last part of the command).

Just copy the command and past it into the command prompt hit enter.

◦IKEv2:
devcon.exe install c:\Windows\inf\netavpna.inf MS_AgileVpnMiniport
◦IP:
devcon.exe install c:\Windows\inf\netrasa.inf MS_NdisWanIp
◦IPv6:
devcon.exe install c:\Windows\inf\netrasa.inf MS_NdisWanIpv6
◦Network Monitor:
devcon.exe install c:\Windows\inf\netrasa.inf MS_NdisWanBh
◦L2TP:
devcon.exe install c:\Windows\inf\netrasa.inf MS_L2tpMiniport
◦PPPoE:
devcon.exe install c:\Windows\inf\netrasa.inf MS_PppoeMiniport
◦PPTP:
devcon.exe install c:\Windows\inf\netrasa.inf MS_PptpMiniport
◦SSTP:
devcon.exe install c:\Windows\inf\netsstpa.inf MS_SstpMiniport

Once done, reboot. Again

This should resolve your issue. 

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