I have 27 inch Samsung space monitor with resolution of 1440p and it's refresh rate is 144hz. I'm only able to set the refresh rate to 60 when using my laptop. UHD 620 can support 4k 60fps, so it technically should support 1440p at least at 120hz, since that requires the same amount of bandwith. However, I can not set the refresh rate over 75hz at any resolution. I'm using HDMI 2.0 cable, which came with the monitor, and the monitor is designed to work perfectly using HDMI, so that can't be the problem. Also if it was older 1.4, it would still be able to provide 120hz at 1080p.
Therefore I'm assuming the maximum refresh rate is somehow controlled?
My laptop also has gtx 1050, but windows says the external monitor is connected to UHD 620.
The Intel graphics tool notices the higher rates:
My rules regarding cables that come with monitors are (a) they are absolute crap and (b) what part of 'they are absolute crap' didn't you understand? Throw it away and purchase a good quality, HDMI 2.0-certified (not 'compliant') cable.