Dell U2422H 23.8" 16:9 IPS Monitor - Manual (Page 39)

Setting Up the Monitor
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Connecting the Monitor for DP Multi-Stream Transport (MST) Function
NOTE: This monitor supports the DP MST feature. To make use of this
feature, your PC Graphics Card must be certified to at least DP1.2 with
MST option.
NOTE: Remove the rubber plug when using DP out connector .
Connecting the Monitor for USB-C Multi-Stream Transport (MST)
Function (U2422HE Only)
NOTE: The maximum number of supported monitors via MST is
subjected to the bandwidth of the USB-C source.
NOTE: Remove the rubber plug when using USB-C upstream connector
.
NOTE: Remove the rubber plug when using DP out connector.