Applies to: Plugable TBT4-UDX1 only; host, OS, hardware revision and monitor-mode conditions still apply.
Identify this exact dock
One built-in HDMI port is sufficient for the documented two-HDMI-screen arrangement because the second screen uses a downstream Thunderbolt adapter.
Match the complete model printed on the unit. Up to two 4K60 screens on a suitable host. Use HDMI plus a downstream Thunderbolt video route. Plugable TBT4-UDX1: HDMI and downstream Thunderbolt displays
Which port is for what?
| Connection | Label or purpose |
|---|---|
| Computer | Front host Thunderbolt port |
| Screen 1 | HDMI output |
| Screen 2 | Downstream Thunderbolt with the supplied USB-C-to-HDMI adapter or suitable video cable |
This is a functional port reference, not a drawing of the physical socket positions. Follow the labels on your unit. Plugable TBT4-UDX1: HDMI and downstream Thunderbolt displays
Before connecting
Up to 100 W advertised; 96 W certified host delivery. Confirm a strict 100 W requirement.
Use the intended powered-dock setup and host cable. Record each monitor’s input, resolution and refresh rate. Keep those requirements separate from the dock’s total port count.
Bring the desk up one screen at a time
- Connect the specified power supply to the dock.
- Connect the laptop using front thunderbolt host port.
- Attach one screen on a listed video path and select its wired input.
- Confirm the operating system recognizes that screen before adding another supported screen.
- Select the required modes and an extended desktop where supported. Check charging, reconnecting and your essential applications.
A useful check when something fails
If only the second screen fails, confirm it is attached to a downstream Thunderbolt port, then test the adapter with one known-good monitor. Base M1/M2 MacBooks retain their one-screen native limit; base M3 needs its closed-lid conditions.
Change one part of the arrangement at a time. Keep a note of the working monitor, cable and port so you can reproduce the result. If the remaining requirement has no documented answer, ask the manufacturer about the exact models instead of assuming the entire dock is defective.
Is it worth buying or replacing?
Check what is included with the actual unit, particularly a used one. The missing USB-C-to-HDMI adapter changes the full setup cost. A backwards HDMI-to-DisplayPort cable is not a substitute.
Use the setup checklist to compare complete arrangements, including any adapters and separate charger. The evidence here is documentation-based; Connect Your Dock has not physically tested this desk.
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