This issue is most likely being caused by either your antivirus software or the Windows 7 firewall.
I suggest that you temporary disable the anti-virus and firewall. Then, try to connect to the VPN again. If the issue persists, I suggest you use a program to sniff your traffic on the Windows 7 box and find out exactly where the packets are dying.
Have you or the server administrator looked at the logs on the VPN server to see if you have any clues or the event viewer on your Win 7 client?
This is the take on that error code from MSFT...
The network connection between your computer and the VPN server was interrupted. This can be caused by a problem in the VPN transmission and is commonly the result of internet latency or simply that your VPN server has reached capacity. Please try to reconnect to the VPN server. If this problem persists, contact the VPN administrator and analyze quality of network connectivity
An error code 807 typically is either the client or the server is behind a NAT device and does not pass through GRE protocol 47. If GRE protocol 47 isn't pass through the NAT device you'll get 807. you'll also get 807 if port 1723 isn't forwarded from the NAT device to the VPN server if the server is behind a NAT device. VPN servers usually have packet filters which restrict inbound connection to only PPTP or L2TP.
I do know that if you run RRAS on the Windows 2003 box, Windows 7 will connect to the RRAS using PPTP behind a NAT device that passes through PPTP GRE protocol 47 and you have forwarded port 1723 to the RRAS box. Maybe this is the issue in 2012 also.
For thatyou may want to specify in your VPN connection the TYPE. Go to properties of your VPN, Networking Tab, Choose PPTP in the drop down.
When you are connecting the connection dialogue will say "Connecting to....". This step is the VPN client trying to communicate with the VPN server using the TCP port 1723. If during this step your vpn just sits there saying Connecting to... and then times out and gives you an error message then you now know that something between you and the VPN server is blocking TCP port 1723. One easy way to "get a second opinion" is to telnet to port 1723. You do so by opening a command prompt (Windows key + R, type CMD and hit enter). You then type this: telnet 126.96.36.199 1723
Substitute 188.8.131.52 with the IP Address or DNS Name of your VPN server. If you are successful the CMD window will go blank with a blinking cursor. If you are being blocked then you will get a message saying Connect Failed. If you get the message "command not recognized", you don't have the telnet client installed (See "Turn On/Off Windows Features" to install it).
If you cannot connect to that port it is likely a firewall or nat issue in your win7 box.
So the bottom line of all my rambeling is that There is a good chance that it is a firewall issue either in the Windows software firewall or in your nat.
Hope this helps. Good luck