Add an annotation: "Remember to update your equipment from the manufacturer's site"
Since the last update of MacOS, it was no longer possible for me to use my 2 screens with my macbook 12 "and my dell docking station.
Even uninstalling / reinstalling Displaylink nothing helped.
The solution: Connect my Dell D6000 dock to a Windows PC and make the update available on the Dell site.
Everything has been working again. If some are having problems with their docking stations, perhaps an update is available on the manufacturer's website.