Kubuntu multimonitor woes and fixes
I have had some problems with Kubuntu working well with multimonitor setup. I use X11 so the reason is most likely there, not just Kubuntu's fault.
When booting up my PC and ending up in SDDM, I see the login screen in both screens. Bit weird, but fine. I can live with that.
However after logging in, my first screen would always reset to 60hz and my second would be 144hz. Saving my first monitor to 144hz and restarting the PC would reset that.
I feel like the problem is that the SDDM doesn't remember my settings or something, but I managed to fix it so I don't have to think about it anymore and here's how.
First, the fix
First, set your monitor settings correct with the Kubuntu display settings.
Then open terminal and do the following command
xrandr'
You should be getting something like this:
Screen 0: minimum 320 x 200, current 3840 x 1080, maximum 16384 x 16384
DisplayPort-0 connected 1920x1080+1920+0 (normal left inverted right x axis y axis) 521mm x 293mm
1920x1080 60.00 + 143.85* 119.98 99.93 50.00 59.94
1680x1050 59.95
1280x1024 75.02 60.02
1440x900 59.89
1280x960 60.00
1280x800 60.00
1152x864 75.00
1280x720 60.00 50.00 59.94
1440x576 50.00
1024x768 75.03 70.07 60.00
1440x480 60.00 59.94
800x600 72.19 75.00 60.32 56.25
720x576 50.00
720x480 60.00 59.94
640x480 75.00 72.81 66.67 60.00 59.94
720x400 70.08
DisplayPort-1 disconnected (normal left inverted right x axis y axis)
HDMI-A-0 disconnected (normal left inverted right x axis y axis)
HDMI-A-1 disconnected (normal left inverted right x axis y axis)
DVI-D-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 531mm x 298mm
1920x1080 60.00 + 144.00* 119.98 99.93 59.94
1680x1050 60.00
1280x1024 119.96 75.02 60.02
1440x900 119.85
1280x800 60.00
1152x864 75.00
1280x720 60.00
1024x768 119.99 75.03 60.00
832x624 74.55
800x600 119.97 75.00 60.32
640x480 75.00 60.00 59.94
720x400 70.08
Copy this part somewhere, you will base your settings to this text. The start behind the hz rating is what you're using at the moment. It will list all the resolutions and hz available to all ports you have connected. Notice that even if your monitor may be marked 144hz, it can be a bit different. Like for me it is 143.85 for my other monitor.
Open Xsetup file for editing
sudo nvim /usr/share/sddm/scripts/Xsetup
(Use your editor of choice :P )
In there, add the following to end of the file
xrandr --output FirstMonitor --mode resolution --post 0x0 --rate hz --primary
xrandr --output SecondMonitor --mode resolution --rate hz
So for me, that is
xrandr --output DVI-D-0 --mode 1920x1080 --pos 0x0 --rate 144 --primary
xrandr --output DisplayPort-0 --mode 1920x1080 --rate 143.85
Save the file, then move on to next file:
sudo nvim /etc/sddm.conf
In there, add following under the [XDisplay], and if it doesn't exist, you can just add it there.
[XDisplay]
DisplayCommand=/usr/share/sddm/scripts/Xsetup
This will make the SDDM load the script you just edited. It may already be there, so you don't necessarily have to add anything.
Reboot and see if it helps.
Second, the groaning
I totally agree I shouldn't have to do anything like this to set up my multimonitor setup. Computer should automatically do this when I save my settings in the GUI.
I think this may just be a bug somewhere, because it did work before I updated to Kubuntu 21.10, and I have reported it as well as I could.
Anyways, part of Linux is doing tinkering like this. I don't mind it, but I am slightly groaning that I had to do this manually.
And please, report all the bugs you find. That's the best way we can get these issues solved, since in the end it's a community run system.
I firmly believe that what I get in free software, I pay in having to fill in bug reports. And I am totally fine with that, personally.
+++
PS. I'm writing this on my birthday!
Woop!