4k 60hz

Hi there I have a Surface Book 2 and a HP Notebook. Both Notebooks should connect to a 4K display with 60fps. I bought an i-Tec USB-C Dock but when connected to the SB2 I have only 30fps on the display. With the HP Notebook every works fine (same i-Tec Dock, same cables and so on). Any ideas on...

Trying to use this tv: https://www.amazon.com/VIZIO-D40u-D1-40-inch-Ultra-Smart/dp/B01A0LGV06/ref=cm_cr_arp_d_product_top?ie=UTF8 as a 4k monitor at 60hz with my surface pro 4. Only able to get it to work at 4k 30hz. Using this adapter...