After installing Debian 9.5.0 with Gnome Desktop, I'm unable to change the display resolution through 'Settings'. The only option I have is 1024 x 768. My display's actual resolution is 1280 x 1024. I am using an Intel Core i5-8400 with Intel UHD Graphics 630. I am not using a discrete graphics card. I have tried removing the xserver-xorg-video-intel package and tried adding a new mode using xrandr --newmode but receive a 'Failed to get size of gamma...' error. Are there any drivers I need to install? Is there anything I can do to change the resolution manually? Thanks for any help!
I solved this by updating the kernel to version 4.15 or above. I added the stretch-backports source in APT, and then installed the newest kernel version. Versions 4.14 and below do not support Coffee Lake graphics.