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Alex
Asked: 2020-12-04 17:11:19 +0800 CST

KVM switch not showing image on secondary screen

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Trying to set up my XPS 9570 on Ubuntu 20.04 with this KVM switch: https://www.amazon.ca/gp/product/B08F1XGTBN/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1

I can use the keyboard and mouse that are connected to the kvm switch and I can detect the screen in my Ubuntu display settings, I can even grag the mouse off the laptop screen.

However I see no image on the moonitor and the monitor doesn't detect any signal.

The KVM works for sure though because when I switch to the windows box the screen lights up.

I did notice that my NVidia X server doesn't seem to detect the second monitor now though.

Any ideas?

In case it can help:

alex@alex-XPS-15-9570:~$ xrandr
Screen 0: minimum 320 x 200, current 6400 x 2160, maximum 16384 x 16384
eDP-1 connected primary 2560x1440+3840+0 (normal left inverted right x axis y axis) 344mm x 194mm
   3840x2160     60.00 +  59.98    59.97  
   3200x1800     59.96    59.94  
   2880x1620     59.96    59.97  
   2560x1600     59.99    59.97  
   2560x1440     59.99    59.99*   59.96    59.95  
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 connected 3840x2160+0+0 (normal left inverted right x axis y axis) 698mm x 393mm
   3840x2160     60.00*+  60.00    50.00    59.94    30.00    25.00    24.00    29.97    23.98

Tried NVidia and Intel video and no difference.

kvm-switch monitor 20.04

2 Answers

  1. Found the solution, I'm returning the KVM switch and buying and peripheral switcher instead, I'll just change the input on my moonitor manally... Not much of an answer I know, but I'm super busy at the moment and didn't feel like troubleshooting this, I'm just answering this so that people don't waste time trying to help me when I won't be able to test it.

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  2. I had a similar problem connecting Windows 10 (Lenovo ThinkPad) and Ubuntu 20.04 (Acer Aspire) to a single monitor (LG 35") with a VCOM KVM Switch DD221-4K.

    First, in Displays settings, I had an unknown display. To be able to remove the unknown display, on the Additional Drivers tab of Software & Updates, I selected the Using NVIDIA driver metapackage from nvidia-driver-390(propirietary, tested) option, then clicked Apply Changes, and then restarted Ubuntu.

    Second, I pressed the KVM switch button and held on for over 5 seconds to be able to refresh the virtual monitor as mentioned in the User Manual.

    After doing these, I was able to switch between computers with the KVM switch button. I can also decide, which screen (External Only, Built-in Only) Ubuntu will use as a Single Display with the Super+P shortcut.

    Displays settings and Additional Drivers

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