Lenovo ThinkPad 40AF0135US User Manual page 18

If the problem persists, disconnect all connections of the dock and uninstall the device driver of the
dock. Then, reinstall the device driver and reconnect all cables to the dock. See Chapter 2 "Setting up
the dock" on page 5.
2. I cannot play back videos on the external display but can play them back on the computer display.
Some computers do not support the Certified Output Protection Protocol (COPP), so you cannot play
back the protected videos on the external display connected to the dock.
To play back videos on the external display, connect the external display to an available DisplayPort or
HDMI connector on your computer. Then extend the video output from your computer display to the
external display. For more information, see "Configuring the external displays" on page 10.
3. The images on the external display flutter.
Check the resolution of the external display and ensure that you use the recommended resolution. For
more information, see "Configuring the external displays" on page 10.
4. The images on the external display are not in correct colors.
Check the color quality of the external display and adjust it to meet your needs. For more information,
see "Configuring the external displays" on page 10.
5. The computer can play back Web flashes. However, when I drag the window to the external
display and maximize the playback window, the playback stops.
To solve the problem, update your Adobe Flash Player program to the latest version.
Audio
I cannot hear anything through my computer speakers or I cannot use the audio connector on the
computer.
By default, Lenovo computers use the audio connector on the dock and disable the built-in audio connector
on the computer when the dock is connected. However, you can manually enable the built-in audio
connector on the computer. For more information, see "Using the audio connector" on page 7.
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ThinkPad Hybrid USB-C with USB-A Dock User Guide