Docked mode refresh rate.

So I'm looking up my rog ally x to my moniter,this way I get more use out of it. I have a dell s3222 gaming moniter capable of 144hz and I'm using a 4k hdmi to usb cable,though I can also use a 4k hdmi cable as well since I have my ally x docked in a jsaux dock. Anyway when hooked up to my moniter it says im currently only getting 60hz refresh.any ideas what's up? Is it the wrong cable?