You can use this connector to connect to a network which supports the DCS protocol like DCS or XLX.
The easiest way is to use the Quick setup to connect to these networks.
DCS and XLX servers usually do not need a valid D-STAR registration, but you can check your callsign's registration by clicking on the Check D-STAR registration button.
You can switch reflectors using your radio by starting a short call to their names as the destination callsign (URCALL), like DCS001 A, or XLX001 A. You can also switch to REF/XRF servers by this method - switching this way changes openSPOT2's active connector.
As the openSPOT2 is designed to be always connected, the unlink (U) command is not interpreted. If you really want to disconnect, you can switch to a config profile which has the Null connector activated.