You might see this message if your router has outdated firmware. To get firmware updates, contact your router's manufacturer or go to the manufacturer's website.
This message might also appear when a connection to a virtual private network (VPN) server cannot be established using either Point-to-Point Tunneling Protocol (PPTP) or Layer Two Tunneling Protocol (L2TP). Here are some things to check:
Verify that the server name is correct and the connection you are trying to use has been configured correctly for your computer.
Make sure that a firewall is not blocking the connection.
Verify that you have a current computer certificate or that the preshared key is correct.
For additional help, contact the administrator of the VPN server.