Dual Monitor Resolution issue

[nam]

Hi All
Need some help troubleshooting.

I have a Lenovo X280 with Dual Dell U2179D monitors. I want to run both monitors at there default of 2560 x 1440. I connected both monitors and laptop to https://www.startech.com/Cards-Adap...lt-3-dock-usb-3-1-laptop-compatible~TB3CDK2DP , but when both monitors are connected over DP i only get 2048 x 1080 at 59Hz on both Monitors.

Any help here please. Is this the limitation of my docker or my Laptop

Thank you

 

[COYS]

I'm not familiar with it but is page 18 of the manual any help?

https://sgcdn.startech.com/005329/media/sets/TB3CDK2DP/TB3CDK2DP_usermanual.pdf

 

[Hades]

Could it be the number of Thunderbolt lanes on that particular USBC port? e.g. you need enouigh lanes for a certain bandwidth?

EDIT: 4 lanes needed for dual 4K displays. Not sure how many lanes needed for dual 1440p. But I think the X280 only has 2 lanes?