Second Monitor Won't Work?

[PhysicistSarah]

I cloned my system from one comptuer to a new computer and now the second monitor won't work.

The monitor says that it is recieving the signal from the laptop, but nothing on the screen, and system settings/displays can't see it.

Not sure what happened. It could be that it is using AMD/Vega hardware now.

How would I restore the second monitor usage?

Here is the output from `inxi -G`

[mick.kde]

I have a different card/monitor but the same issue:

mick@mick-HP-EliteBook-8770w:~$ inxi -G
Graphics:
Device-1: NVIDIA GK104GLM [Quadro K3000M] driver: nvidia v: 390.129
Display: x11 server: X.Org 1.20.5 driver: modesetting,nouveau,nvidia
unloaded: fbdev,vesa resolution: 1600x900~60Hz
OpenGL: renderer: Quadro K3000M/PCIe/SSE2 v: 4.6.0 NVIDIA 390.129

I have an AOC monitor (USB) which I carry with me when I travel. Presently, it's just dead weight. I look forward to responses from our more knowledgeable colleagues.

Mick

[sithlord48]

What are you seeing in the display settings?

@Mick does your laptop have a hotkey for displays like fn F8?

[mick.kde]

What are you seeing in the display settings?

@Mick does your laptop have a hotkey for displays like fn F8?

Yes, it's fn F4 and it allows me to manipulate the two monitors, e.g. extend right, extend left, disable one or the other. I can do the same things with System Settings and Displays. The drawback is when I drag the cursor across the USB monitor, I get a smeared mess with the cursor "repainting" the screen in swaths. AOC does provide a Ubuntu driver which was easy to install but it hasn't gotten me to the promised land just yet.

[PhysicistSarah]

What are you seeing in the display settings?

@Mick does your laptop have a hotkey for displays like fn F8?

My laptop does have a F4 key which toggles monitor settings, but nothing happens since it doesn't detect the other monitor.

Even in system settings / displays, there is no second monitor. It just simply doesn't see it.

[claydoh]

I have a different card/monitor but the same issue:

mick@mick-HP-EliteBook-8770w:~$ inxi -G
Graphics:
Device-1: NVIDIA GK104GLM [Quadro K3000M] driver: nvidia v: 390.129
Display: x11 server: X.Org 1.20.5 driver: modesetting,nouveau,nvidia
unloaded: fbdev,vesa resolution: 1600x900~60Hz
OpenGL: renderer: Quadro K3000M/PCIe/SSE2 v: 4.6.0 NVIDIA 390.129

I have an AOC monitor (USB) which I carry with me when I travel. Presently, it's just dead weight. I look forward to responses from our more knowledgeable colleagues.

Mick

This is likely a different issue than the OP's, so a separate thread may be warranted.,
But there is thjis:
https://github.com/AdnanHodzic/displaylink-debian

[claydoh]

My laptop does have a F4 key which toggles monitor settings, but nothing happens since it doesn't detect the other monitor.

Even in system settings / displays, there is no second monitor. It just simply doesn't see it.

Have you tried swapping cables, just to eliminate the possibility of a bad one?

I recently moved to a new PC, and was having issues with my TV/monitor dual screen setup that ended up being a dodgy cable, despite working just fine on the previous system using the same screen setup and same OS drive, on the same graphics card. The monitor was not being detected at all.