HP TB4 Dock G6 Display Routing and Port Priority Issues Between Windows (MST) and macOS (SST)

[MarlonKn]

Hello,

I am writing to request technical assistance regarding port priority and stream assignment on the HP Thunderbolt 4 G6 Dock. My setup consists of three monitors connected simultaneously: two 2K high-refresh-rate displays connected via DisplayPort and the downstream Thunderbolt 4 port, alongside a third 1080p display connected via the dock's HDMI port (or a DP-to-HDMI adapter).

This setup is shared between a Windows laptop and an Apple Silicon MacBook. On the Windows host, Multi-Stream Transport (MST) functions as expected, allowing all three displays to run concurrently. On macOS, due to the single-stream limitations of Apple Silicon, I only expect two displays to be driven natively. However, the dock consistently assigns hardware priority to the HDMI signal path instead of routing the two primary DisplayPort streams.

Consequently, when the MacBook is connected, the dock forces the secondary 1080p HDMI monitor to take precedence, which starves or disables the downstream Thunderbolt 4 video tunnel. As a result, macOS activates the wrong monitor pair instead of driving the two 2K high-refresh displays connected to the native DisplayPort and downstream TB4 outputs.

Is there a known firmware behavior, port hierarchy rule, or workaround that allows the dock to prioritize native DisplayPort and downstream Thunderbolt streams over the internal HDMI pipeline when a non-MST (macOS) host is detected? Any guidance on how to force the dock to pass through the correct dual video pipelines to macOS without physically unplugging the third monitor each time would be greatly appreciated.

Thank you for your assistance.
Best regards,

Marlon K.

[Jerry_57]

Hi @MarlonKn,
 

Welcome to the HP Support Community.

Thank you for the detailed explanation of your configuration.

Based on HP documentation, Apple Silicon macOS does not support Multi-Stream Transport (MST). Because of this limitation, HP Thunderbolt G6 docks cannot use MST-based display expansion on macOS in the same way they can when connected to a Windows system. 

For MacBook Pro systems with Apple Pro or Max chipsets, HP supports up to two native external displays through the Thunderbolt G6 dock when one display is connected through the dock's downstream Thunderbolt port and the second display is connected through either DisplayPort, HDMI, or USB-C DisplayPort Alt Mode. 

If maintaining three active displays is required while using Apple Silicon macOS, a DisplayLink-based adapter or dock solution would be the recommended approach, as HP documentation identifies DisplayLink as the supported method for extending beyond Apple's native display limitations. 
 

I hope this clarifies the behavior. Please let us know the exact MacBook model and chip (M1, M2, M3, or M4; base, Pro, Max, or Ultra) if you would like us to verify the officially supported display topology for your configuration.

I hope this will help.

 

Take care and have a good day.

[MarlonKn]

Thank you for the reply @Jerry_57. However, DisplayLink is unfortunately not an option for my setup due to corporate IT policies prohibiting third-party software installation on my work laptop, as well as the additional CPU/RAM resource overhead.

To clarify: I completely accept that macOS will natively drive only 2 of the 3 connected displays. My goal is not to get 3 active displays on macOS, but to control WHICH 2 displays the dock presents to the Mac.

When only the two 2K monitors are connected (via DisplayPort and the downstream TB4 port), macOS drives both of them perfectly at full resolution and refresh rate. However, as soon as the 3rd (1080p HDMI) monitor is plugged into the dock—either via the native HDMI port or via a DP-to-HDMI adapter—the dock’s internal hardware automatically prioritizes the HDMI stream and starves/disables the downstream TB4 video tunnel. This forces macOS to output to the 1080p display instead of the second 2K display.

Is there any custom firmware, hidden setting, or workaround to override this hardware port priority, so the dock favors downstream TB4 over the HDMI pipeline when connected to a non-MST host without needing to physically unplug cables?

[Jerry_57]

Thank you for your response.

Workarounds (Without Unplugging Cables)

Since you cannot use DisplayLink and cannot modify the dock's internal hardware logic, you must alter how the signal is delivered to the Mac or how the monitors are controlled.

Use a Bidirectional USB-C / DisplayPort Switch:
Leave all cables plugged into the dock. Put a hardware switch between the dock's HDMI/DP port and the 1080p monitor. When you switch to the Mac, click the physical button on the switch to "disconnect" the 1080p monitor electronically. The dock will immediately restore bandwidth to the downstream TB4 port.
 

• Utilize Monitor Input Selection (If Supported):
  Some monitors stop drawing active bandwidth from a port when switched to a different input. If your 1080p monitor has multiple inputs, switching its input away from the dock (e.g., to an empty input) might signal to the dock that the port is inactive, though this depends heavily on the monitor's EDID behavior.
   
• Bypass the Dock for the Second 2K Monitor:
  Connect the second 2K monitor directly to a secondary native Thunderbolt port on your Mac using a separate USB-C to DP/HDMI cable. This bypasses the dock's restrictive MST hub entirely and gives you full control over the display topology.