I’m having exactly same problem as https://forum.nomachine.com/topic/nomachining-to-a-mac
When I remote from Windows 10 into a MacBook pro (with high resolution). It can only transfer at 1728×1117. Increasing the resolution in NoMachine also changes the scaling – makes the text too small.
Screenshot 1 is the remote session; the display setting says “1728×1117,” but it actually means “looks like 1728×1117”, meanwhile, my screen resolution is 3456×2234. I suspect NoMachine has recognized this wrong resolution and transferred data at a low rate.