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My Monitors Are Not Detected When My Mac Wakes from Sleep or Boots. What Can I Do?

Last Update: August 29th, 2026
Article ID: 2582592

Summary

If an external monitor is not detected after your Mac wakes from sleep or starts up, the monitor's automatic input-source detection feature may be contributing to the issue.

Setting the monitor to use the specific HDMI, DisplayPort, or USB-C input connected to your Plugable product can help the monitor reconnect more reliably.

Applicable To

This article applies to:

  • Macs using external displays
  • Plugable docking stations and video adapters used with macOS
  • Monitors that support automatic input-source detection

Depending on the monitor manufacturer, automatic input detection may be called Auto Select, Auto Detect, Auto Source, Input Auto Switch, or something similar.

Answer

Some monitors automatically scan their available video inputs when waking from sleep or when a connected computer starts.

In certain configurations, this additional input-switching behavior can interfere with the timing of display detection, resulting in the monitor remaining blank or not appearing in macOS Display Settings.

If this occurs, disable automatic input-source detection and manually select the input connected to the Plugable product.

Disable Automatic Input-Source Detection

The exact steps vary by monitor model, but the setting is typically available through the monitor's built-in on-screen display (OSD).

  1. Open the monitor's on-screen display menu.
  2. Locate the Input, Source, or similar settings menu.
  3. Disable any automatic input-selection option, such as:
    • Auto Select
    • Auto Detect
    • Auto Source
    • Input Auto Switch
  4. Manually select the input being used with the Plugable product, such as:
    • HDMI
    • DisplayPort
    • USB-C
  5. Put the Mac to sleep and wake it again to test the connection.

For instructions specific to your monitor, refer to the monitor manufacturer's documentation.

If the Display Is Still Not Detected

If disabling automatic input detection does not resolve the issue:

  1. Open Apple menu > System Settings > Displays.
  2. Press and hold the Option key. The Detect Displays button should appear.
  3. Select Detect Displays.

You can also try:

  • Disconnecting and reconnecting the Plugable product
  • Power cycling the monitor
  • Trying a different video cable
  • Restarting the Mac
  • Installing the latest available macOS updates

If you are using a Plugable DisplayLink-based docking station or USB graphics adapter and the displays work after you log in but remain blank before login, this is a different issue.

DisplayLink Manager normally begins running after you log in to macOS. DisplayLink provides an optional Login Screen Extension for users who need DisplayLink-connected displays available before login.

For more information, see:

Why Don't My DisplayLink-Connected Screens Show Anything Before Logging Into macOS?

Need Assistance?

If your external displays are still not detected after completing the steps above, please contact Plugable Support at support@plugable.com.

  • When contacting support, please include:
  • Your Plugable product model
  • Your Mac model
  • Your macOS version
  • The make and model of each connected monitor
  • How each monitor is connected to the Plugable product
  • A description of what happens after waking or starting the Mac
  • The output from Plugable's diagnostic tool, PlugDebug