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A few days ago ubuntu restarted unexpectedly and after rebooting the second screen was not recognised at all. It has been working for some weeks without any problem and it is plugged through HDMI.

After browsing the web I found a quick solve using this command.

$sudo dpkg-reconfigure LightDM it opens a screen with following options

  1. LightDM
  2. gdm3
  3. lightdm

It was setted up to gdm3 and I changed it to lightdm After switching to lightdm the second screen is working again, when I plug it in it seems is working but it is really laggy. Tabs take ages to open, webcam is really slow and cuts the video. Typing takes a lot of time to appear on the screen. Switching between tabs is incredibly slow... It does not work at all even though it looks like it is.

So I decided to try setting up back to gdm3 and despite monitor is being recognised as well, it shows up just half screen and I cannot see the bottom part.As well as if I use the other option LightDM.

screen

I have also tried to change nvidia driver version but computer got blocked while installing them...

Do you know how can I fix this? or at least what the problem is so I can browse the internet for a solution???

Thanks in advance

Albercv
  • 21

2 Answers2

0

The second screen issue is resolved using Videonauth's solution on Ask Ubuntu:

You need to edit /etc/gdm3/custom.conf, change this line:

[daemon]
# Uncoment the line below to force the login screen to use Xorg
#WaylandEnable=false

to

[daemon]
# Uncoment the line below to force the login screen to use Xorg
WaylandEnable=false

After I've did that, I switched to gdm3 again and now the second screen is working. But, is still incredibly slow whenever I change browser tabs, and opening program screens takes ages. Whereas, if I do it the laptop screen it works normally.

Blindspots
  • 3,472
Albercv
  • 21
0

Had exactly the same problem. In my case, a second display would be recognized if connected via USB-C, but not via HDMI.

I solved it by autoinstalling drivers after the upgrade to Ubuntu 21:

sudo ubuntu-drivers autoinstall   
sudo reboot

For context, it's a laptop with a dedicated NVIDIA RTX GPU.

swimmer
  • 101