Problems with XPS 9343 external display

Hello fellas,

I am running Windows 10 on my XPS 9343 laptop and I'm trying to connect it to an external 21:9 (2560:1080) monitor. It cant seem to detect that it is 21:9, and just runs at 1080p. When I try to force the resolution to 2560:1080 I get a dialogue saying:

I usually run Ubuntu Gnome on this but am currently forced to be Windows 10 for UniSim and EndNote support (just has to be that way, no way round it). It runs the display absolutely fine with Ubuntu. The i5 5200U can run much larger displays than this, too.

I suspect the problem lies with the detection of HDMI 1.3/1.4 or something. The HDMI cable is connected via a mini displayport adapter. What is super confusing is that its fine when with Ubuntu. I have tried the newest display drivers from both Intel and Dell. On a side note, the display also has noticeable lag and a fuzzy-ish look. But first things first...

Does anyone have any clue as to whats going on? Any pointers would be much appreciated. There are some solutions out there saying "get a new cable", but that wont help me.

it is a problem with the drivers. make sure you are selecting your monitor.

also adapters dont play well with intel drivers

Not sure what you mean by that. Select it in the driver control panel? Yeah did that.

Then why is it great with Ubuntu? Strange. Thought it would be golden on Windows.

ubuntu uses different drivers than windows. yeah the windows driver cant properly detect max screen size.