Dell U2913WM User Manual page 23

The default out of factory setting in the U2913WM is DP1.1a.
To enable MST connection please use only DP cable as provided in box (or other DP1.2 certified cable) and change the DP setting to DP1.2 by performing the below steps:
A) Monitor is able to show content
1. Use OSD button to navigate to Other Settings
2. Go to DisplayPort 1.2 selection
3. Select Enable or Disable accordingly
4. Follow the screen message to confirm selection of DP1.2 or DP1.1a