Using Two Monitors in Ubuntu 20.04

Until two days ago, using two monitors in Ubuntu 20.04 was no problem. However, since yesterday, this is not possible anymore, even though I did not change the cable setup or anything. Also, when I go to "Settings"-->"Displays", it shows me "Unknown Display" whereas previously it had showed me the two connected monitors. I have an Nvidia GPU built in, any help would be appreciated.

Edit 1: Interesting, this problem does not occur under Windows where I can use my two monitors without any problems. My setup is a tower PC, an Nvidia GeForce GT 610 is built in.

Edit 2: The problem is solved now, cf. the accepted answer.

Solution 1:

This kind of problems is typically related to driver issues. Check if, in grub, booting to an earlier kernel solves the problem.

Also, identify when was the last boot

$ journalctl --list-boots

and update (output may well be in excess of what is needed, but it doesn't hurt)

$ zgrep "linux" /var/log/dpkg.log* | grep " install "
$ zgrep "nvidia" /var/log/dpkg.log* | grep " install "

In addition to posting this output, please post the output of

$ inxi -v 2
$ xrandr
$ ubuntu-drivers devices

If you don't have inxi and/or ubuntu-drivers you can install them with sudo apt install inxi ubuntu-drivers.

If you don't have the latest nvidia drivers, I suggest you install them with, e.g.,

$ sudo apt install nvidia-driver-470

and reboot.

Solution 2:

Two monitors with Ubuntu 20.04 LTS - now with the Linux driver nouveau

I have a somewhat similar system [as the original poster]. I updated and upgraded my Ubuntu 20.04 LTS in a Dell m4800 with nvidia graphics.

After reboot it can still feed two screens, one internal monitor and a 40 inch TV. I have them 'side by side' and can move windows from the internal monitor to the TV with the touchpad.

But I noticed that the system had automatically turned off the proprietary driver and was using nouveau (the free Linux driver). The performance playing video is good, I did not notice any significant difference in quality.

It works also for the original poster to switch to the free Linux driver, nouveau, and it can be a good alternative also for other users who are affected by this problem. (Let us hope that there will soon be a working solution with a proprietary nvidia driver too.)

To switch the drive, go to "Software & Updates", then under "Additional Drivers" and finally choose the Nouveau driver.