Question about Lenovo ThinkPad Docking

I have this docking station in combination with a ThinkPad X240 and newly with an Asus ROG Swift PG348Q with a resolution of 3440x1440. Unfortunately, the picture always flickers (sometimes the screen goes out for several seconds). When I connect the screen to my gaming computer, everything works perfectly. The Displayport cable has also been changed. Is it possible that the docking station is defective? This problem does not occur when connected to another monitor via the DVI output.