I don't consider myself a linux guru. I'm not sure about what information I need to provide. I will gladly update my question if you give me the instructions.

Setup

HP Spectre x360 - 13-4190nz with Ubuntu 18.10

Office

laptop resolution: 2560x1440

second monitor: mini-display to hdmi, 2560x1440 primary

third monitor: hdmi 2560x1440

Home

laptop resolution: 2560x1440

second monitor: mini-display to hdmi, 1920x1080 primary

third monitor: hdmi 1920x1080

Note: I'm not entirely sure if my setup at home is exactly correct. I won't be home before a few days.

Detail of the problem

Whenever it's at home nor at the office, once I pass the login screen, Ubuntu detects only one of my external monitors and the screen is "unstable". The screen starts and stops like it has a bad contact or is badly connected. Once I open the Display Arrangement and change something, it fixes until the next reboot.

Information

Graphic card

▶ sudo lshw -class display

*-display                 

   description: VGA compatible controller

   product: Skylake GT2 [HD Graphics 520]

   vendor: Intel Corporation

   physical id: 2

   bus info: pci@0000:00:02.0

   version: 07

   width: 64 bits

   clock: 33MHz

   capabilities: pciexpress msi pm vga_controller bus_master cap_list rom

   configuration: driver=i915 latency=0

   resources: irq:148 memory:de000000-deffffff memory:c0000000-cfffffff ioport:f000(size=64) memory:c0000-dffff

Drivers

▶ lspci -nnk | grep -i vga -A3

00:02.0 VGA compatible controller [0300]: Intel Corporation Skylake GT2 [HD Graphics 520] [8086:1916] (rev 07)

    Subsystem: Hewlett-Packard Company Skylake GT2 [HD Graphics 520] [103c:81a1]

    Kernel driver in use: i915

    Kernel modules: i915

00:13.0 Non-VGA unclassified device [0000]: Intel Corporation Sunrise Point-LP Integrated Sensor Hub [8086:9d35] (rev 21)

    Subsystem: Hewlett-Packard Company Sunrise Point-LP Integrated Sensor Hub [103c:81a1]

    Kernel driver in use: intel_ish_ipc

    Kernel modules: intel_ish_ipc

xrandr config

▶ xrandr

Screen 0: minimum 320 x 200, current 7680 x 1440, maximum 8192 x 8192

eDP-1 connected 2560x1440+0+0 (normal left inverted right x axis y axis) 293mm x 165mm

   2560x1440     60.07*+  59.99    59.99    59.96    59.95    40.05  

   1920x1440     60.00  

   1856x1392     60.01  

   1792x1344     60.01  

   2048x1152     59.99    59.98    59.90    59.91  

   1920x1200     59.88    59.95  

   1920x1080     60.01    59.97    59.96    59.93  

   1600x1200     60.00  

   1680x1050     59.95    59.88  

   1600x1024     60.17  

   1400x1050     59.98  

   1600x900      59.99    59.94    59.95    59.82  

   1280x1024     60.02  

   1440x900      59.89  

   1400x900      59.96    59.88  

   1280x960      60.00  

   1440x810      60.00    59.97  

   1368x768      59.88    59.85  

   1360x768      59.80    59.96  

   1280x800      59.99    59.97    59.81    59.91  

   1152x864      60.00  

   1280x720      60.00    59.99    59.86    59.74  

   1024x768      60.04    60.00  

   960x720       60.00  

   928x696       60.05  

   896x672       60.01  

   1024x576      59.95    59.96    59.90    59.82  

   960x600       59.93    60.00  

   960x540       59.96    59.99    59.63    59.82  

   800x600       60.00    60.32    56.25  

   840x525       60.01    59.88  

   864x486       59.92    59.57  

   800x512       60.17  

   700x525       59.98  

   800x450       59.95    59.82  

   640x512       60.02  

   720x450       59.89  

   700x450       59.96    59.88  

   640x480       60.00    59.94  

   720x405       59.51    58.99  

   684x384       59.88    59.85  

   680x384       59.80    59.96  

   640x400       59.88    59.98  

   576x432       60.06  

   640x360       59.86    59.83    59.84    59.32  

   512x384       60.00  

   512x288       60.00    59.92  

   480x270       59.63    59.82  

   400x300       60.32    56.34  

   432x243       59.92    59.57  

   320x240       60.05  

   360x202       59.51    59.13  

   320x180       59.84    59.32  

HDMI-1 connected 2560x1440+5120+0 (normal left inverted right x axis y axis) 597mm x 336mm

   2560x1440     59.95*+

   1920x1080     60.00    60.00    50.00    50.00    59.94  

   1680x1050     59.88  

   1600x900      60.00  

   1280x1024     75.02    60.02  

   1440x900      59.90  

   1280x800      59.91  

   1152x864      75.00  

   1280x720      60.00    60.00    50.00    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    60.00    59.94    59.94  

   640x480       75.00    72.81    66.67    60.00    59.94  

   720x400       70.08  

DP-1 connected primary 2560x1440+2560+0 (normal left inverted right x axis y axis) 597mm x 336mm

   2560x1440     59.95*+

   1920x1080     60.00    60.00    59.94  

   1680x1050     59.95  

   1600x900      60.00  

   1280x1024     75.02    60.02  

   1440x900      59.89  

   1280x800      59.81  

   1152x864      75.00  

   1280x720      60.00    59.94  

   1024x768      75.03    70.07    60.00  

   832x624       74.55  

   800x600       72.19    75.00    60.32    56.25  

   640x480       75.00    72.81    66.67    60.00    59.94  

   720x400       70.08  

HDMI-2 disconnected (normal left inverted right x axis y axis)

~/.config/monitors.xml

▶ cat ~/.config/monitors.xml

<monitors version="2">

  <configuration>

    <logicalmonitor>

      <x>4480</x>

      <y>0</y>

      <scale>1</scale>

      <monitor>

        <monitorspec>

          <connector>HDMI-1</connector>

          <vendor>ACI</vendor>

          <product>VS278</product>

          <serial>H5LMQS008692</serial>

        </monitorspec>

        <mode>

          <width>1920</width>

          <height>1080</height>

          <rate>60</rate>

        </mode>

      </monitor>

    </logicalmonitor>

    <logicalmonitor>

      <x>2560</x>

      <y>0</y>

      <scale>1</scale>

      <primary>yes</primary>

      <monitor>

        <monitorspec>

          <connector>HDMI-2</connector>

          <vendor>ACI</vendor>

          <product>ASUS VK278</product>

          <serial>B7LMTF079618</serial>

        </monitorspec>

        <mode>

          <width>1920</width>

          <height>1080</height>

          <rate>60</rate>

        </mode>

      </monitor>

    </logicalmonitor>

    <logicalmonitor>

      <x>0</x>

      <y>0</y>

      <scale>1</scale>

      <monitor>

        <monitorspec>

          <connector>eDP-1</connector>

          <vendor>LGD</vendor>

          <product>0x0000</product>

          <serial>0x00000000</serial>

        </monitorspec>

        <mode>

          <width>2560</width>

          <height>1440</height>

          <rate>60.074672698974609</rate>

        </mode>

      </monitor>

    </logicalmonitor>

  </configuration>

  <configuration>

    <logicalmonitor>

      <x>5120</x>

      <y>0</y>

      <scale>1</scale>

      <monitor>

        <monitorspec>

          <connector>HDMI-1</connector>

          <vendor>SAM</vendor>

          <product>S27H85x</product>

          <serial>H1AK500000</serial>

        </monitorspec>

        <mode>

          <width>2560</width>

          <height>1440</height>

          <rate>59.950550079345703</rate>

        </mode>

      </monitor>

    </logicalmonitor>

    <logicalmonitor>

      <x>2560</x>

      <y>0</y>

      <scale>1</scale>

      <primary>yes</primary>

      <monitor>

        <monitorspec>

          <connector>DP-1</connector>

          <vendor>SAM</vendor>

          <product>S27H85x</product>

          <serial>H1AK500000</serial>

        </monitorspec>

        <mode>

          <width>2560</width>

          <height>1440</height>

          <rate>59.950550079345703</rate>

        </mode>

      </monitor>

    </logicalmonitor>

    <logicalmonitor>

      <x>0</x>

      <y>0</y>

      <scale>1</scale>

      <monitor>

        <monitorspec>

          <connector>eDP-1</connector>

          <vendor>LGD</vendor>

          <product>0x0000</product>

          <serial>0x00000000</serial>

        </monitorspec>

        <mode>

          <width>2560</width>

          <height>1440</height>

          <rate>60.074672698974609</rate>

        </mode>

      </monitor>

    </logicalmonitor>

  </configuration>

</monitors>