Applies to: MacBook Air with base M3, macOS Sonoma 14.3 or later, WD22TB4. Documentation-based setup, not a hands-on certification.

A concrete desk: ports and cables

Two independent external screens, with the Mac lid closed. Apple requires power, an external keyboard and mouse/trackpad, and macOS Sonoma 14.3 or later. The example uses one DisplayPort monitor and one HDMI monitor, each targeting 4K60.

Apple MacBook Air · base M3Dock host Thunderbolt cable → Mac Thunderbolt portDell WD22TB4
  1. Dock DisplayPort outputDisplayPort cable rated for 4K60Screen 1 · DisplayPort input
  2. Dock downstream ThunderboltUSB-C video → HDMI adapter + HDMI cable, rated for 4K60Screen 2 · HDMI input
Connection schematic, not physical socket positions. Match the labels on your equipment.

Source scope: Apple: two displays on a Mac with base M3 · Dell: Thunderbolt docks with Apple hosts

What you need for this arrangement

  • 1
    WD22TB4 power supply and its host cable

    Keep the original dock power arrangement.

  • 1
    DisplayPort cable

    Screen 1; verify 4K60 at both endpoints.

  • 1 + 1
    USB-C-to-HDMI video adapter and HDMI cable

    Screen 2; the USB-C end is the source at the dock.

  • 1 set
    External keyboard and mouse/trackpad

    Needed with the lid closed; keep Mac power connected.

Check the box contents and the cables you already own before ordering. Monitor and dock model names alone do not identify a cable’s mode rating or direction.

If this exact arrangement fails

Both screens show the same window
Move screen 2 to a downstream Thunderbolt port. Two ordinary DP/HDMI paths on this dock do not create independent Mac desktops.
One screen disappears when the lid opens
That is the base-M3 display limit. Close the lid again after checking power and external input devices.
Only the HDMI screen is dark
Select the monitor’s HDMI input, then test the USB-C video adapter with that screen alone.
  1. Connect only screen 1 and record its working input and mode.
  2. Add the next screen on the labelled route. Confirm separate windows on each screen.
  3. Check every selected mode, a sleep/wake cycle and a reconnect. Record any failure before changing another component.

Confirm the requirements

Apple specifies a closed lid, external keyboard and mouse or trackpad, power, and macOS Sonoma 14.3 or later for this Air’s two-display mode. Opening the lid changes the available external-display arrangement. Apple: two displays on a Mac with base M3

For a conservative starting target, configure two 4K displays at 60 Hz only when every component supports it. Apple’s maximum modes and a dock’s maximum modes are separate ceilings; neither alone certifies your complete desk.

Use this connection arrangement

Connect display A through the dock’s DisplayPort output, and display B through a downstream Thunderbolt port using a compatible USB-C video cable or adapter. Do not mistake a general-purpose USB-C socket for that Thunderbolt output. This topology follows Dell’s Apple-host guidance. Dell: Thunderbolt docks with Apple hosts

The diagram below is an original wiring explanation, not a photograph of the dock. Locate the labelled connectors in the WD22TB4 manual before plugging in. Cable orientation matters when using a directional adapter.

Bring the screens up in stages

  1. Connect the WD22TB4 to its required power adapter, then connect its host cable to the Mac. Keep storage transfers stopped while changing the setup.
  2. Attach the external keyboard and pointing device. Connect display A and select the matching input on its on-screen menu.
  3. Confirm that the Mac receives power. Use the Mac’s charger if the dock’s power delivery is not working.
  4. Close the laptop and connect display B on the separate downstream Thunderbolt path.
  5. Open Displays settings using the external screen, choose an extended arrangement, and place the screens in the order they occupy on your desk.

If the second screen is dark

Test each display alone using the known-good connection. If both work individually, revisit the lid state and port labels before replacing either monitor. If one fails alone, diagnose that screen, input, cable and adapter first.

Dell’s Apple article states a firmware scope for WD22TB4. Have your IT team or the appropriate supported update environment check the dock when its history is unknown. An update should follow the manufacturer’s model-specific instructions; do not interrupt its power.

When another purchase makes sense

Buy only after naming the missing capability. An adapter may solve a connector mismatch; it will not change the laptop’s open-lid display limit. If you need the built-in display and two native external displays simultaneously, this M3 Air setup does not meet that requirement. Review the different M4 Air case before comparing laptops.

Separate a lid-state failure from an accessory failure

Before closing the lid, confirm that the external keyboard and pointing device actually control the Mac. If the dock charges but these devices are unavailable, unlock the laptop and check accessory approval. That is a separate check from Apple’s two-display lid requirement.

When the screen disappearsNext useful observation
Only when the lid opensCompare with the M3 Air native-display arrangement.
After an ordinary sleep with the lid still closedRecord power, input-device response and which reconnect restores it.
Even when tested aloneReturn to that screen’s input and cable before investigating the two-display limit.

Use the wake log if the setup succeeds initially but fails later.

Sources & scope

These instructions combine published references with our proposed diagnostic sequence. This setup has not been physically tested by Connect Your Dock. Manufacturer documents can change; use the exact model and scope linked below.

How we assess evidence