[RESOLVED] Multiple Monitor Support

[heresy]

When trying to use multiple monitors (extended) not replicated with different resolutions it skews the image on both screens. Anyone else suffering the same issue?

[heresy]

The solution if anyone is interested is to run in konsole:
xrandr

Make note of your displays names. and in my case this resolved the using x.11:
xrandr --fb 1920x1080 --output LVDS1 --mode 1280x800 --scale-from 1920x1080 --output DVI1 --mode 1920x1080 --scale 1x1 --same-as LVDS1

wayland is even more unstable

[heresy]

Sorry this should have probably gone in the desktop environment support. I am new the to forum.

[Schwarzer Kater]

Welcome.

Some more information about you hardware (system) and your exact settings/set-up could help to solve your problem.

In general one of the first things you can do in a Linux system when problems occur is to test if they are still there in a new user account.
But in your case I suppose it was a fresh installation of Kubuntu 24.04 LTS anyhow, so there are e.g. no old settings or cache files in your user account?

[heresy]

Thats correct, Fresh install on a laptop. Nothing old was kept.

Primary laptop display 1280 x 800 (16:10) and external monitor is 1920 x 1080 (16:9).

This laptop was previously running Kubuntu 18.04 LTS with Pro with no issues, I had stuck with that as the kernel support in 20.04 wasnt very good with realtek DVB-T usb dongle I had. I never bothered with 22.04 just out of laziness really. But I was keen on 24.04 and everything is working great. however multimonitor support is broken.

I wish I could screen grab it, but bascially the external monitor squishes the display of the 16:10 laptop display into a 16:9 and the external monitors display is bled over the two screens however the locations of buttons etc are exactly where they should be. ie you need to press on an area about an inch or 2.5cm to the right of the button to get it to work.

[heresy]

you can actually cause the problem on a single display.

go into display configuration, change your resolution to something else, change it back and monitor is all messed up until you reboot.

[Schwarzer Kater]

you can actually cause the problem on a single display.

go into display configuration, change your resolution to something else, change it back and monitor is all messed up until you reboot.

Not in my three systems I just have tested this with…

Perhaps you have an Nvidia GPU?
Or you are using Wayland ?
Or both?

[heresy]

Its an intel gpu and using the default x.11. Other distros are suggesting its an KDE 5.27 problem and to change to wayland as a fix or some heavy manual editing of x.11 conf files. I will give wayland a go.

[Schwarzer Kater]

To try Wayland in Kubuntu 24.04 LTS you have to sudo apt update && sudo apt install plasma-workspace-wayland first.

Afterwards you can change to the Wayland session on the log-in screen.

[heresy]

Using wayland fixes the issue! Unfortunately its not as stable, random but infrequent hard freezing. Also lose a bit of functionality, ie display replcation. I am going to edit the input methods to see if that is related to why its unstable and go from there.

[heresy]

Change all the IM and did some adjusting. Wayland works great for the desktop and fixes the multiple display issue. Unfortunately, the random app rendering and freezing still persists. I think I will roll back to previous LTS until 24.04.1 is released. Im sure I cant be the only one suffering this issue.

[Schwarzer Kater]

It has not been that long since 24.04 has been released…
Perhaps you can already find a solution within the coming weeks when others also have had this problem - if not I hope that the issue will be resolved for you with the release of 24.04.1 !

[heresy]

I actually did find a solution using xrandr. However 24.04 is still unstable. I would consider it still in beta. I will wait for 24.04.1 and see if issue is either resolved or use xrandr and see if the release stable.

[heresy]

The solution if anyone is interested is to run in konsole:
xrandr

Make note of your displays names. and in my case this resolved the using x.11:
xrandr --fb 1920x1080 --output LVDS1 --mode 1280x800 --scale-from 1920x1080 --output DVI1 --mode 1920x1080 --scale 1x1 --same-as LVDS1

wayland is even more unstable

[shishimaru]

Hello, what do you mean with "skews"?

Here's what happens on my Kubuntu 24.04: reboot the system, find the desktop as if it was "moved" at least more than half to the right. The left side is not usable, has the plymouth theme applied. Cannot click, cannot put any window.

How to solve: use another resolution and then again the native one, but every time I reboot it's always the same. Wayland corrects this, but uses a lot of cpu even with Nvidia driver 550.

It's absolutely weird, because it has never happened before this new install. I think there's something in the updates that is breaking this. I will eventually try to reinstall once again and tell if it goes better, but I'll wait a bit since it took me a whole day just to install. Otherwise, I'll have to abandon Kubuntu and go on Ubuntu. KDE Neon is not an option since it uses an almost unstable version of KDE on a very stable version of Ubuntu, with no real support for Nvidia. OpenSUSE never works.

A desktop shouldn't behave like this It should be very smooth: turn the laptop ON, it just works whenever I change resolution, stop.