Ubuntu 20.04.5 WideScreen Monitor with 3440x1440 always goes back to 1920x1080

I got a new Monitor (34" - 3440x1440 - 144hz) for my Laptop, but as I started it the Monitor was completely black. In the settings the Monitor was available but disabled. When I enabled it and want to save, it disabled automatically.

The Monitor only works if I change the resolution to 1920x1080 - 60hz or 3440x1440 - 29.9hz. But if I want to change it to 3440x1440 - 60hz, it automatically goes back to the previous settings with 29.9hz.

Does someone know how I can make the resolution 3440x1440 with 60hz work? Or is there a problem with my graficcard? I got an onboard amd renoir.

EDIT:

╰─ xrandr
Screen 0: minimum 320 x 200, current 6440 x 1920, maximum 16384 x 16384
eDP connected 1920x1080+0+840 (normal left inverted right x axis y axis) 344mm x 194mm
   1920x1080     60.02*+  48.02  
   1680x1050     60.02  
   1280x1024     60.02  
   1440x900      60.02  
   1280x800      60.02  
   1280x720      60.02  
   1024x768      60.02  
   800x600       60.02  
   640x480       60.02  
HDMI-A-0 disconnected (normal left inverted right x axis y axis)
DisplayPort-0 disconnected (normal left inverted right x axis y axis)
DisplayPort-1 connected primary 1080x1920+1920+0 left (normal left inverted right x axis y axis) 521mm x 293mm
   1920x1080     60.00*+ 144.00   120.00   119.88   119.98    99.93    50.00    59.94  
   1680x1050     59.88  
   1280x1024     75.02    60.02  
   1440x900      59.90  
   1280x720      60.00    50.00    59.94  
   1024x768     119.99    75.03    70.07    60.00  
   832x624       74.55  
   800x600      119.97    72.19    75.00    60.32    56.25  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       75.00    72.81    66.67    60.00    59.94  
   720x400       70.08  
DisplayPort-2 connected 3440x1440+3000+0 (normal left inverted right x axis y axis) 797mm x 334mm
   3440x1440     59.97 +  29.99* 
   2560x1080     59.98    60.00    59.94    50.00  
   1720x1440     59.94  
   1920x1080    120.00   119.88    60.00    60.00    50.00    59.94  
   1680x1050     59.88  
   1280x1024     75.02    60.02  
   1440x900      59.90  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    70.07    60.00  
   832x624       74.55  
   800x600       72.19    75.00    60.32    56.25  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       75.00    72.81    66.67    60.00    59.94  
   720x400       70.08  
DisplayPort-3 disconnected (normal left inverted right x axis y axis)

The Monitor is connected from HDMI to HDMI.

I also tried the Monitor with another Windows Computer. There it works fine. If I try to boot Linux from USB there is still the same issue.

@Michael, xrandr is showing the current display mode status, a + indicates the preferred mode and a * indicates the current mode.

So eDP is your laptop built-in display. And I assume DisplayPort-1 and DisplayPort-2 are 2 currently connected monitors. Why they are showing as DisplayPort not HDMI I don't know, what is make/model of laptop and are you connected via some sort of dock or laptop adapter?

Anyway, for the 3440x1440 monitor, it is reporting to Ubuntu that the only refresh rates supported at that resolution are 59.97 and 29.99 so it IS reporting that the monitor supports 3440x1440 at 60hz.

Here is a very good resource for xrandr and specifically how to try adding unsupported resolutions: https://wiki.archlinux.org/title/Xrandr#Adding_undetected_resolutions

So I suggest you try those instructions using cvt to generate a modeline like:

cvt 3440 1440 60

and if that does not work try reduced blanking mode:

cvt -r 3440 1440 60