Old 4K Display (Asus PQ321) using DisplayPort-Multi-Stream gets displayed as two screens

since a long time i wanted to make the jump from Windows to Linux. But my old Asus PQ321 Screen puts a spoke in the wheel.

As its one of the first 4k Screens it consists of two panels build into one screen. Each panel has a resolution of 1920x2160 therefore they have in sum a resolution of 3840*2160.

The monitor is connected to a Nvidia Geforce 1080 Ti via Mini-DisplayPort cable (Mini Display Port is the only connector on the monitor beside of Analog VGA).

Operating System is Ubuntu 21.10 using Drivers from Nvidia (495.46).

I cant get the display to work as just one Screen.

I played around with NVIDIA TwinView in my xorg.conf but nothing works.

xrandroutput:

Screen 0: minimum 8 x 8, current 3840 x 2160, maximum 32767 x 32767
DP-0.8 connected primary 1920x2160+0+0 (normal left inverted right x axis y axis) 349mm x 393mm
   1920x2160     60.00*+  50.00  
   1920x1200     59.95  
   1920x1080     60.00    59.94    50.00    23.98  
   1680x1050     59.95  
   1600x1200     60.00  
   1440x900      59.89  
   1400x1050     59.98  
   1280x1024     75.02    60.02  
   1280x960      60.00  
   1280x800      59.81  
   1280x720      60.00    59.94    50.00  
   1024x768      75.03    70.07    60.00  
   800x600       75.00    72.19    60.32    56.25  
   720x576       50.00  
   720x480       59.94  
   640x480       75.00    72.81    59.94  
DP-0.1.8 connected 1920x2160+1920+0 (normal left inverted right x axis y axis) 349mm x 393mm
   1920x2160     60.00*+  50.00  
   1920x1200     59.95  
   1920x1080     60.00    59.94    50.00    23.98  
   1680x1050     59.95  
   1600x1200     60.00  
   1440x900      59.89  
   1400x1050     59.98  
   1280x1024     75.02    60.02  
   1280x960      60.00  
   1280x800      59.81  
   1280x720      60.00    59.94    50.00  
   1024x768      75.03    70.07    60.00  
   800x600       75.00    72.19    60.32    56.25  
   720x576       50.00  
   720x480       59.94  
   640x480       75.00    72.81    59.94  
DVI-D-0 disconnected (normal left inverted right x axis y axis)
HDMI-0 connected (normal left inverted right x axis y axis)
   2560x1440     59.95 +  74.97  
   2048x1080     60.00    24.00  
   1920x1080     60.00    59.94    50.00    25.00    23.98    60.00    50.04    50.04  
   1600x900      60.00  
   1280x1024     75.02    60.02  
   1280x720      59.94    50.00  
   1152x864      75.00  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       59.94  
   640x480       75.00    59.94    59.93  
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)

I recreated the xorg.conf file with the command nvidia-xconfig as my last fruitless tries killed my system. Therefore its currently in its original status:

xorg.conf

# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig:  version 495.46

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0"
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
EndSection

Section "Files"
EndSection

Section "InputDevice"
    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"
    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Unknown"
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

xorg.conf after pasting data from nvidia-settings:

# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings:  version 470.57.01

# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig:  version 495.46

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0" 0 0
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
    Option         "Xinerama" "0"
EndSection

Section "Files"
EndSection

Section "InputDevice"

    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"

    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Ancor Communications Inc PQ321"
    HorizSync       24.0 - 140.0
    VertRefresh     20.0 - 77.0
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "NVIDIA GeForce GTX 1080 Ti"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "Stereo" "0"
    Option         "nvidiaXineramaInfoOrder" "DFP-3.8"
    Option         "metamodes" "DP-0.1.8: nvidia-auto-select +1920+0, DP-0.8: nvidia-auto-select +0+0"
    Option         "SLI" "Off"
    Option         "MultiGPU" "Off"
    Option         "BaseMosaic" "off"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

Thank you very much!