External HDMI display not detected

Hello, I recently tried to install QubesOS on my laptop (with a GTX 3060 mobile) and encountered the same issue with the graphics drivers that I used to have on Fedora (booting with a black screen), which required me to blacklist the nouveau driver using the parameter nouveau.modeset=0 in Grub before installation… This workaround worked, and I was able to boot and successfully install QubesOS. However, my external monitor was not being detected, a common issue related to my GPU with Linux distros, requiring the installation of proprietary NVIDIA drivers for my external monitor to be detected. Following this guide (Nvidia driver installation - #2 by dhn) and this guide (Nvidia proprietary driver installation) to install the latest recommended version of the proprietary NVIDIA driver for my GPU (550.90.07 released on June 4th, which worked flawlessly with Linux Mint), I completed the installation successfully, as shown by the commands mentioned in the second referenced guide:

[user@dom0 ~]$ lsmod | grep nvidia
nvidia 60583936 0 
[user@dom0 ~]$ lsmod | grep nouveau
[user@dom0 ~]$

Despite this, my external monitor remains undetected, whether I boot with it connected to my laptop or not, the xrandr command output consistently displayed only my laptop’s display, as shown below

xrandr.log:

[user@dom0 ~]$ xrandr
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 16384 x 16384
eDP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 194mm
   1920x1080    144.00*+  60.01    59.97    59.96    60.00    59.93  
   1680x1050     59.95    59.88  
   1400x1050     74.76    59.98  
   1600x900      59.99    59.94    59.95    59.82  
   1280x1024     85.02    75.02    60.02  
   1400x900      59.96    59.88  
   1280x960      85.00    60.00  
   1440x810      60.00    59.97  
   1368x768      59.88    59.85  
   1280x800      59.99    59.97    59.81    59.91  
   1152x864      75.00  
   1280x720      60.00    59.99    59.86    59.74  
   1024x768      85.00    75.05    60.04    85.00    75.03    70.07    60.00  
   1024x768i     86.96  
   960x720       85.00    75.00    60.00  
   928x696       75.00    60.05  
   896x672       75.05    60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   832x624       74.55  
   960x540       59.96    59.99    59.63    59.82  
   800x600       85.00    75.00    70.00    65.00    60.00    85.14    72.19    75.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   700x525       74.76    59.98  
   800x450       59.95    59.82  
   640x512       85.02    75.02    60.02  
   700x450       59.96    59.88  
   640x480       85.09    60.00    85.01    72.81    75.00    59.94  
   720x405       59.51    58.99  
   720x400       85.04  
   684x384       59.88    59.85  
   640x400       59.88    59.98    85.08  
   576x432       75.00  
   640x360       59.86    59.83    59.84    59.32  
   640x350       85.08  
   512x384       85.00    75.03    70.07    60.00  
   512x384i      87.06  
   512x288       60.00    59.92  
   416x312       74.66  
   480x270       59.63    59.82  
   400x300       85.27    72.19    75.12    60.32    56.34  
   432x243       59.92    59.57  
   320x240       85.18    72.81    75.00    60.05  
   360x202       59.51    59.13  
   360x200       85.04  
   320x200       85.27  
   320x180       59.84    59.32  
   320x175       85.27  
[user@dom0 ~]$

I have experimented with various kernel versions and different NVIDIA driver versions on previous clean QubesOS installations, yet the issue persisted. I am unsure of what steps to take next. Can someone assist me in identifying the root cause and finding a solution to this problem?

You should try checking that xorg.conf is correctly set up, sometimes you might need to manually adjust it to properly use NVIDIA card.

You can also check /var/log/Xorg.0.log and see if there are any errors