Question about Dell S3422DWG

I am working with a Dell XPS 15 9560 laptop (GeForce GTX 1050 graphics card) and a D3100 docking station. No matter how I plug in the cables (e.g. HDMI also directly to the laptop; DP is only available on the docking station), the maximum selectable resolution is always too small, so the picture is distorted. Drivers are all updated. What could be the reason for this?