The second monitor fell off, ubuntu, how to fix it?

Question

linux

When two monitors are connected, at boot both work, after the system boots, only one works, which shows the ubuntu 18.04 desktop background (i.e. the second monitor). When you poke the hdmi connector, sometimes the second one connects, but flies when you reboot. When booting from ubuntu live cd both work fine. The connectors are connected to the built-in video card.

Answer 1

The fact that both monitors are working during the download, and only one at the end of the download, may mean that the other is turned off in the settings.
If you have MATE, you can get into the monitor settings by:

• by entering mate-display-properties
• via the panel menu: System ⇨ Options ⇨ Hardware ⇨ Screens

Probably other graphical environments (Gnome, KDE, etc.) have something similar, I'm not sure (if you have Gnome, take a look at man gnome-control-center ).