Getting a 4K external screen working with a Surface Book 2

I note that there are many posts around the Internet about this topic - how to get a Surface Book 2 driving a single external 4K screen.
Many authors state that the screen is always reported as a HD scren 1920x1080.
This is what I found:
The lowering of the resolution can be simply related to the use of HDMI to drive the screen.
Now I am not saying it is not possible with HDMI but an immediate solution is simply to ditch HDMI and use the DISPLAY PORT connections from Surface Book 2 to screen.
Hold on you say, there isn't a mini display port socket on a Surface Book 2.
Yep true - you will need a Surface Dock and then you will be given two.
Just connect from the mini display port on the Dock to the Display port input on the screen, tell your screen to accept input from the Display Port and Voila!
Hope this helps someone.