Applies to: CalDigit TS4 with the Apple silicon Mac models linked here. This is a documented connection plan, not a measured performance review.

A concrete desk: ports and cables

Two independent 4K60 external screens on an M4 MacBook Air: one DisplayPort input and one HDMI input. Base M1/M2 MacBooks retain their native one-screen limit; use the chip-specific section below before applying this map to another Mac.

Apple MacBook Air · M4 exampleSupplied Thunderbolt cable → TS4 Computer portCalDigit TS4
  1. TS4 DisplayPort outputDisplayPort cable rated for 4K60Screen 1 · DisplayPort input
  2. TS4 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: CalDigit: TS4 specifications and host requirements · CalDigit: Mac display support by chip and dock · Apple: MacBook Air display support · Apple: MacBook Air M2 (2022) specifications

What you need for this arrangement

  • 1
    TS4 supply and supplied Thunderbolt host cable

    Connect the host to Computer, not an accessory USB-C port.

  • 1
    DisplayPort cable

    Screen 1 uses the built-in DP output.

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

    Screen 2 uses downstream Thunderbolt. For HDMI on the DP path instead, CalDigit requires an active DP-to-HDMI adapter.

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

The second USB-C connection gives no video
Check that it is a downstream Thunderbolt port. Ordinary USB-C data sockets are not interchangeable.
An HDMI adapter on the DP output fails
Confirm it is an active DisplayPort-source to HDMI-display adapter, rated for the target mode.
The same desk works on M4 but not base M2
The host display limit changed. A TS4 cannot add the missing native display stream to base M2.
  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.

Start with the Mac, then the dock

CalDigit’s Mac support chart distinguishes chip families rather than treating every MacBook as identical. Use the exact row, then check Apple’s own host specification. CalDigit: Mac display support by chip and dock

Host examplePlanning consequence
MacBook Air M2 (2022)One native external display; the TS4 does not add a second native stream.
MacBook Air M3Two external displays require Apple’s power, input-device, OS and closed-lid conditions.
MacBook Air M4Two external displays can coexist with the laptop screen.

Apple: MacBook Air M2 (2022) specifications · Apple: two displays on a Mac with base M3 · Apple: MacBook Air display support

Select the actual display outputs

TS4 provides DisplayPort and downstream Thunderbolt connections. For an HDMI-only monitor, CalDigit specifies an active DisplayPort-to-HDMI adapter for the DisplayPort route, or a suitable USB-C-to-HDMI connection on a downstream Thunderbolt route. CalDigit: TS4 specifications and host requirements

Label the upstream connection “to laptop” before adding screens. Do not put a display cable in a USB-C data-only socket and conclude that the monitor is incompatible. The dock’s connector map matters as much as the monitor input.

Bring up one independent desktop at a time

  1. Power the TS4 with its supplied adapter and use the specified host cable.
  2. Connect one monitor, select its wired input, and confirm a picture.
  3. Connect the second through another supported output path. Apply the M3 Air lid requirements if relevant.
  4. In Displays settings, arrange the screens and move different windows onto them.
  5. Record each screen’s selected resolution and refresh rate, then test a normal sleep/wake cycle.

If the result is incomplete

A second dark screen on a base M2 Air is a host-limit question. Two detected screens with one failing only at a higher mode are a bandwidth, cable or display-mode question. Keep those cases separate. This guide does not claim that every advertised high-resolution mode is available simultaneously through every adapter.

Before replacing the dock, test the failing display directly and test each dock path alone. If both displays work alone, keep those working cables and investigate the combined arrangement with the exact Mac and TS4 support tables.

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