A plug connector includes a housing having a cable opening for receiving a cable with a plurality of wires. A plurality of contacts are arranged within a contact insert. A retention pin is arranged within the contact insert, the retention pin having a base and a protruding portion. The protruding portion of the retention pin is configured to engage a socket insert of a socket connector through a socket contact opening when the plug connector is plugged into the socket connector. A diameter of the protruding portion of the retention pin exceeds a diameter of the socket contact opening. The retention pin resiliently deforms during unplugging the plug connector and thereby increases its withdrawal force.