Well I have a problem with getting a server I have to open a web browser by default across 3 identical displays. On the server I also have 3 Identical nvidia k5000 video cards. The cards are all synced together. we have run the same configuration using Ubuntu 12 and Ubuntu 16. In all cases we could span any open window or web browser across 3 screens (4k) with no problems.

It seems as if something new in Ubuntu 18 is stopping me from spanning anything but the desktop backdrop.

details

First let me say I have tried almost all the suggestions posted here and none worked. I have rebuilt the server to see if that would help and it did not.This is very frustrating and do not understand why it is not working....

server running Ubuntu18 lts 3 nvidia cards Quadro K5000 sync'ed 3 planar displays 4k 86 inch. UR8651-MX Nvidia driver used version 460.73.01 and 465 also 390

my xorg.conf file This worked on ubuntu 12 and 16 but Not on 18

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

Section "Extensions"
    Option         "Composite" "Disable"
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 "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "Quadro K5000"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "PHR"
    ModelName      "Planar Systems, Inc. UR8651-MX"
    HorizSync       14.0 - 135.0
    VertRefresh     23.0 - 85.0
    Option         "DPMS"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "Stereo" "0"
    Option         "nvidiaXineramaInfoOrder" "DFP-0"
    Option         "MetaModes" "GPU-0.DFP-0: 3840x2160_30 +0+0, GPU-1.DFP-0: 3840x2160_30 +3840+0, GPU-2.DFP-0: 3840x2160_30 +7680+0"
    Option         "SLI" "Mosaic"
    Option         "MultiGPU" "Off"
    Option         "BaseMosaic" "off"
    SubSection     "Display"
        Depth       24
        Modes       "3840x2160_30
    EndSubSection
EndSection

Please let me know if i am forgetting ang information. Again I have been at this for 6 months and tried almost everything on this sight and others. did they get rid of spanning a web browser or any open window? please any help or advice will help.