Abnormal Display on External Monitor Connected to Dock and Dock Connected to Computer with Ubuntu OS

There are four possible symptoms:

• When a DisplayPort and HDMI monitor are connected to K2 Dock, the HDMI monitor cannot output.
• After connecting to TBT/DP or TBT/HDMI monitors on the K2 Dock and restarting the computer, the DP or HDMI monitor cannot output.
• After connecting an external monitor to a dock on the list below and then restarting or suspend the computer, the external monitor is blinking after computer resumed.
• There is only one display output on the Dell Dock - WD19S when over one monitor is connected to the dock.

Affected Platforms:

• Dell Pro Rugged 13 RA13250
• Dell Pro Rugged 14 RB14250

Affected Docks:

• Dell Dock - WD19S
• Dell Pro Dock WD25
• Dell Pro Smart Dock SD25
• Dell Pro Thunderbolt 4 Dock WD25TB4
• Dell Pro Thunderbolt 4 Smart Dock SD25TB4
• Dell Pro Thunderbolt 5 Dock WD25TB5
• Dell Pro Thunderbolt 5 Smart Dock SD25TB5

The panel replay of Display Stream Compression (DSC) function is enabled it has compatibility issues with Multistream Transport (MST) mode.

Updating the Ubuntu Kennel driver to version 6.17 or later on the computer resolves the issue.

There are two options to manually update the Ubuntu Kennel driver:

Option 1:

1. Launch the Software Updater app and check Security updates. 
2. Tap Install Now in the bottom right corner.
    

Option 2:

1. Launch the terminal by clicking the left bottom Ubuntu icon, search for terminal and launch.
2. Type sudo apt update & sudo apt upgrade
    

Check the Ubuntu Kennel version:

1. Launch the terminal.
2. Type uname-a