Forticlient VPN SSL Stops at 40%

It is very strange your computer can not manage login to VPN via forticlient. you try connect to VPN SSL Fortigate and stop at 40% , and come out message error "Unable to establish the VPN connection. The VPN server may be unreachable (-5)".

There is two ways fix this problem. 

Change your MTU interface computer via command prompt

• Click the "Windows Button" on the task bar.
• Click "All Programs".
• Click "Accessories".
• Right Click on "Command Prompt" then click "Run as adminstrator".
• Then type "netsh interface ipv4 show subinterface".
• Press Enter

          you will see a list of network interface

          Note :

• If your connection using wireless then change MTU on "Wirelless Network Connection"

• If you connection using cable then change MTU on "Local Area Network"

• Type "netsh interface ip4 set subinterface wireless network connection mtu=1300 store=persistent"
•  Press Enter and restart your computer

Change your interface MTU computer using Register Editor

• Open regedit as an administrator account
• Navigate to HKLM\System\CurrentControlSet\Services\tcpip\parameters\interface\[Choose the interface in the question] (Do this by checking the correct IP address is in the setting under this key for the adapter you are configuring)
• Once your are in the correct key for your interface, right-click and select new DWORD value (32bit)
• Call it MTU
• Change the Hexadecimal value equal to the setting 514

•  Close the Register Editor window and restart your computer

Now you able to login VPN SSL Fortigate without any problem.