Dell UP2414Q and MBP 13" Early 2015 Integration problem

I have MBP 13" Early 2015 and have a dell 4k up2414q monitor. my aim is to get 4k 60 hz output on dell monitor. I tried to connect both in 2 different ways and couldn't make it work:

1- mini display port to display port cable (this cable came with dell monitor)

When connected MBP starts freezing, cursor does not move properly and blank screen on dell monitor. on mac screen i notice that second monitor is detected.

2- thunderbolt cable (original apple brand)

no signal detection on dell monitor and it is blank screen again.

on dell monitor display port 1.2 is enabled,

i called apple support and they advised me power reset, video reset, we tried but still no solution...

how can i solve this problem? do you think it is worth to get different cables and try?