Mojave : no display after monitor upgrade from FullHD to 1440p

Hello everyone,
I have recently bought a 1440p monitor to upgrade the previous malfunctioning FullHD monitor I used to use.

Unfortunately, it seems the computer does not send any video signal to the monitor.

Is there something I am supposed to change before I can use the 1440p monitor?

Thank you in advance!

Author: CiaoCiao2