Possible Cause: This issue may occur, if the TCP port that is used by the VPN connection is already being used by another program.

Possible Cause: This issue may occur, if the TCP port that is used by the VPN connection is already being used by another program. The VPN connection uses TCP port 1723 to establish a connection. If another program is already using this port, you cannot establish a VPN connection.

Possible Solution: Simply, restart your system then Connect VPN.