Because you wrote Windows picked up the display as General, then the display settings are all up to you and most folk can not deal with that. Even I won't tell you a step by step.
So why not install their monitor drivers from https://www.nec-display-solutions.com/p/uk/en/support/productsupport/rp/2690WUXi.xhtml and try again?
I would be using the DVI input with the usual HDMI to DVI cable.
I have a HDMI or USB-C port on the new HP laptop. Need to connect the NEC MultiSync2690WUXi monitor, which has no HDMI port but 2DVI ports: https://www.nec-display.com/ap/en_display/old/lcd2690/index.html
I tried more cable options: DVI->HDMI, DVI->USB-C, or analog VGA->USB-C. FHD resolution works only with VGA, but that is image of poor quality. DVI can only handle 1280x780, which on a 26"display against 15" 4Kdisplay HP laptop is unacceptable. Windows10 in the monitor settings sees as GeneralPNP display and does not have a higher resolution. Graphics is AMD Radeon RX Vega M 870/4GB.
What to do with it to get it right? Or is it worth returning a laptop and choosing another brand? I don't want to buy a new monitor right now, this one has great color and picture.
thanks for advice