Question Issue with laptop's DisplayPort to external monitor ?

[DefNotWaffle]

So i ran into some problem when I try to use external monitor on my laptop since my internal screen is dead. My laptop is Asus Rog GL503GE and i just recently bought an LG 24GN600-B 144hz monitor for it. When i first try it using hdmi it only supports up to 120hz @ 1080p and it was connected to the iGPU instead of the dGPU. I also bought usb-c to displayport but when i turn it on it said "incorrect displayport version" and im confused because my laptop does support the thunderbolt3 and display port 1.4.

When i change to dp 1.2/1.2 nothing happens, no signal. when i haven't try the mini because of this thread:
https://rog.asus.com/forum/showthread.php?122062-ROG-Strix-GL503-DisplayPort-Misleading

 

[Fix_that_Glitch]

You probably need an active dp adapter.