Dell UltraSharp U2518D User Manual page 29

Connecting the monitor for DP Multi-Stream Transport (MST)
function
NOTE: Supports the DP MST feature. To make use of this feature, your PC
Graphics Card must be certified to DP1.2 with MST option.
NOTE: Remove the rubber plug when use DP out connector.
Connecting the USB cable
Setting Up the Monitor | 29