Applies to: TBT4-UDZ specifically. Screen counts depend on the computer; TBT4-UD5 and older TBT3 docks have different arrangements.
A concrete desk: ports and cables
Two independent 4K60 external Mac screens using one output from each labelled group. Windows four-screen claims do not apply to this Mac path. Base M1/M2 and base M3 have their own limits below.
- Dock group 1 · HDMIHDMI cable rated for 4K60↓Screen 1 · HDMI input
- Dock group 2 · HDMIHDMI cable rated for 4K60↓Screen 2 · HDMI input
Source scope: Plugable TBT4-UDZ: host, output groups and charging · Apple: MacBook Air display support
What you need for this arrangement
- 1TBT4-UDZ supply and supplied Thunderbolt host cable
Match UDZ; UD5 and UDX1 use different output arrangements.
- 2HDMI cables rated for 4K60
One from each labelled group, with HDMI inputs that accept the mode.
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 two external pictures are not independent
- Check the group labels: move one monitor to the other group, then select Extend in macOS.
- A third cable does not add a third Mac desktop
- This dock’s Mac arrangement has a two-screen ceiling, independently of the physical socket count.
- One monitor loses 4K60
- Test its cable and input alone at 4K60 before evaluating both together. Record the exact adapter if any is added.
- Connect only screen 1 and record its working input and mode.
- Add the next screen on the labelled route. Confirm separate windows on each screen.
- Check every selected mode, a sleep/wake cycle and a reconnect. Record any failure before changing another component.
Start with the computer, then choose the sockets
| Your computer | Starting rule | What still needs checking |
|---|---|---|
| Base M1 or M2 MacBook | One native external screen through this dock | An extra socket cannot add a second native workspace. |
| Base M3 MacBook | Two with the required closed-lid arrangement | Air and Pro have different minimum macOS requirements. |
| M4 MacBook or an M-series Pro/Max MacBook | Up to two through this dock | One output from each group; respect the exact host limit. |
| Windows Thunderbolt 4 / USB4 laptop | Up to four is a conditional dock capability | The host graphics limit, internal display and combined output modes matter. |
| Windows Thunderbolt 3 or USB-C video host | A reduced arrangement | Consult the stream and bandwidth table before selecting resolutions. |
A simple two-screen connection
- Connect the powered dock’s front host port to the computer with the intended Thunderbolt cable.
- Choose HDMI or DisplayPort in Group 1 for the first monitor. Select that input on the screen.
- For a Mac, connect the second monitor to Group 2. Do not put both monitors in the same group.
- Choose an extended desktop and move a different window onto each monitor.
- Set the supported picture modes. Check charging and a sleep/wake cycle before relying on the desk.
Avoid the USB-C accessory-port trap
The rear USB-C port is a data/accessory connection. Plugable excludes USB-C and Thunderbolt monitors from this dock’s display outputs. HDMI and DisplayPort monitors are the intended choices. A DisplayPort-to-HDMI conversion requires an active adapter. Plugable TBT4-UDZ: host, output groups and charging
If your monitor has several inputs, inspect those before buying an adapter. Using an existing HDMI or DisplayPort input can be simpler than trying to convert the dock’s output into a USB-C-only display.
When two screens show the same thing
First read the group labels on the dock. Keep one working monitor and cable connected, then add the other screen to the other group. Confirm an extended arrangement in the operating system. If the host only allows one native screen, moving cables cannot change that limit.
For a base M3, use the exact Apple guide linked on your model page. Do not close the lid without providing the required power and external input devices.
Check the whole purchase
Record the dock, host cable, power supply and any active adapters as separate items. The advertised charging ceiling is 100 W, while Plugable also gives a 98 W certified value. A requirement right at that boundary needs confirmation. Plugable TBT4-UDZ: host, output groups and charging
Compare TBT4-UD5 if a downstream Thunderbolt display port matters, or UD-6950PDH if approved DisplayLink software is part of your plan.
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