I've freshly installed Ubuntu 18.04, when I connect HDMI cable to laptop nothing happening. I've googled and found couple of similar issues and run commands like:

xrandr --addmode HDMI-1-1 1920x1080 xrandr --output HDMI-1-1 --mode 1920x1080

However it didn't help, I get: xrandr: cannot find output "HDMI-1-1"

It's not hardware issue as if I boot in Windows 10 I can use the same monitor absolutely without any issues. Also it used to work in 16.04.

I have Lenovo E570 with Nvidia Drivers installed, in Intel only graphic card mode.

Is there any way to make Ubuntu to work with the external monitor?


I had similar experiences when I plugged in my Samsung HDMI-capable TV, and it came up as Unknown Display (in Settings / Display).

In my case, the problem was that my graphics card needed a power-down. Not a reboot, a full power-down.

I spent hours trying and researching xrandr and such, until a power failure made everything work, and sudddenly the PC recognized the TV correctly. Since it works better in Windows, maybe this is a driver issue.(BTW, if HDMI sound and video on the Samsung are out-of-sync, the TV needs a power cycle. Too bad Samsung Support doesn't know this, or won't admit it.)

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