Does not detect monitor, no required resolution, unknown VGA display in Ubuntu

Faced the problem of determining the second monitor connected via VGA. At first, suspicion fell on the drivers, since Ubuntu 18.04 was updated before the reboot. Being engaged in the analysis and witchcraft with xorg.conf achieved nothing. Decided to reinstall the OS, but it did not help. Later I checked the connected monitor to another machine, it became clear that the monitor does not give information about itself. The reasons why, I don't know. Adapters are not used, I tried to change the connection cable, it did not help.

I had to start the "Unknown Display" manually by setting its operation parameters. I remember that it worked with a resolution of 1920x1080 with a frequency of 60. This is quite enough to generate parameters and let the system know how to work with the monitor.

1. Determine the connection of the desired monitor :

in console

xrandr

We see the use (in my case) VGA-1-1

2. We take a line with parameters :

cvt 1920 1080 60

parameters (in my case) 1920x1080 60. We need this part, we will use it further.

3. Apply new parameters :

xrandr --newmode 1920x1080_60.00 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync

xrandr --addmode VGA-1-1 1920x1080_60.00

xrandr --output VGA-1-1 --mode 1920x1080_60.00

1920x1080_60.00 - parameter from screenshot 2.

VGA-1-1 - connection from screen 1.

We observe that in the monitor management settings, the desired resolution has appeared.

This method only works within one session. In order for the monitor to have the parameters we need when logging in, we need to set it to autorun.

4. Automation at startup :

Create monitor.sh with parameters from step 3 above and place it anywhere

#\!/bin/sh

xrandr --newmode 1920x1080_60.00 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync
xrandr --addmode VGA-1-1 1920x1080_60.00
xrandr --output VGA-1-1 --mode 1920x1080_60.00

To auto-start when you turn it on, you need to go to "Settings" -\u003e "Auto-start applications" and do this

Where sh /home/username/monitor.sh is the launch of the executable.

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