Error 806

Error 806: a connection between your computer and the VPN server has been established but the VPN connection cannot be completed. The most common cause for this is that there is at least one internet device between your computer and the VPN server is not configured to allow GRE protocol packets Verify that protocol 47 GRE is allowed on all personal firewall devices or routers. if the problem persists, contact your administrator. Resolutions: 1) if you have a router/firewall, make sure you open TCP Port 1723, IP Protocol 47 (GRE). 2) make sure you can reach the VPN server by using ping. Sometimes, poor connection can cause this issue too. 3) You may need to updated firmware on a router or firewall. 4) The VPN server may not be able to get IP from DHCP for the VPN client.