I have Ubuntu 18.04.6 LTS and used two monitors with 1920x1080 and 1680x1050 for quite some time without any issues. Now I've replaced the 1680x1050 with a bigger screen with 4k resolution (3840x2160) and I can't figure out the way to set them right. I read multiple articles and questions about xrandr (example Running multiple monitors with different DPI), but I always end up with issues in one or both monitors.
The same setup is working fine when connecting them to another laptop running Windows 10.
At the beginning the refresh rate was being updated for both monitors, and now they are independent, but the 4k monitor displays everything as expected, correct resolution but on the right in around 1/10 of it, everything flickers. The other smaller monitor either displays everything blurry, wrong colors and/or display outside of the screen. Now I can't even see the top menu bar with Ubuntu settings (clock, internet connection, power off...).
I've tried multiple commands to setup the right zoom for individual monitors and also in general, but nothing seems to work. This applies for both monitors, so it doesn't work well:
gsettings set org.gnome.desktop.interface text-scaling-factor 1.4375
this is the result of xrandr:
Screen 0: minimum 320 x 200, current 5760 x 2160, maximum 16384 x 16384
DisplayPort-0 connected 3840x2160+1920+0 (normal left inverted right x axis y axis) 697mm x 392mm
3840x2160 60.00*+ 30.00 29.97
2560x1440 59.95
1920x1080 60.00 59.94
1680x1050 59.95
1600x900 60.00
1280x1024 75.02 60.02
1440x900 59.89
1280x800 59.81
1152x864 75.00
1280x720 60.00 59.94
1024x768 75.03 70.07 60.00
832x624 74.55
800x600 72.19 75.00 60.32 56.25
640x480 75.00 72.81 66.67 60.00 59.94
720x400 70.08
HDMI-0 connected primary 1920x1080+0+699 (normal left inverted right x axis y axis) 509mm x 286mm
1920x1080 60.00 + 60.00 50.00 50.00 59.94 30.00* 24.00 29.97 23.98
1920x1080i 60.00 50.00 59.94
1680x1050 59.95
1400x1050 59.95
1600x900 60.00
1280x1024 75.02 60.02
1440x900 59.90
1280x800 59.91
1152x864 75.00
1280x720 60.00 60.00 50.00 59.94
1024x768 75.03 70.07 60.00
832x624 74.55
800x600 75.00 60.32
720x576 50.00
720x576i 50.00
720x480 60.00 59.94
720x480i 60.00 59.94
640x480 75.00 60.00 59.94
720x400 70.08
With the current settings, HDMI-0 is displaying wrong colors, text is blurry and display is a little bit out of screen, but if I try to change the refresh rate to 30, it messes everything displaying even worse.
I also tried this command, but I had to reset xrandr afterwards, because the result was worse, splitting the screen in two and overlapping both screens:
xrandr --dpi 138 --fb 7640x4320 --output DisplayPort-0 --mode 3840x2160 --output HDMI-0 --scale 2x2 --pos 3840x0 --panning 3840x2160+3840+0
It seems I need to select to use one or the other monitor now in order to see at least one clear? Can someone please help?
Thank you!
