Error codes for dial-up or VPN connections - Windows ClientError codes The following list contains the error codes for dial-up connections or VPN connections: 600 An operation is pending. 601 The port handle is invalid. 602 The port is already open. 603 Caller's buffer is too small. 604 Wrong information specified. 605 Cannot set port information. 606 The port is not connected. 607 The event is invalid. 608 The device does not exist. 609 The device type d
