In a single external monitor setup, MST/DP 1.2 should be Disabled. It is only Enabled if you are daisy chaining to a second monitor via the first monitor DP (DisplayPort) out port.
E7440 mDP out port --> U2414H mDP to DP cable --> U2414H DP in port
The U2414H maxes to 1920x1080 60Hz, so you could also just use HDMI =
E7440 HDMI out port --> HDMI to HDMI cable --> U2414H HDMI in port