Recently we wrote about how the latest update to macOS 10.13.4 causes several different types of video devices, including those based on the DisplayLink technology we use in many of our products, to stop working. This loss of functionality is a frustrating development for those of us who have become accustomed to multi-monitor goodness as part of our daily workflow.

With this OS change, the total number of displays that can be connected to Thunderbolt 3 and USB-C Macs is now significantly reduced. Users of our UD-ULTCDL and UD-ULTC4K docks can continue to drive a single monitor connected to the 4K “Alt Mode” HDMI output on their dock. See the table below for information on the total number of monitors your 10.13.4 MacBook supports, and details on which products can be connected to a free Thunderbolt 3 port on your system to connect additional display(s) in conjunction with the monitor connected to your UD-ULTCDL/ULTC4K docking station.

For a more comprehensive look at the display support on specific Mac platforms along with additional options that aren’t based on DisplayLink technology to help ‘get back’ some displays, see additional details below.

Thunderbolt 3 MacBook Pros with AMD GPU

Apple systems that have Thunderbolt 3 ports and also have an internal AMD graphics adapter (GPU) have the most options available, as they can support a maximum of four external displays using a combination of USB-C or Thunderbolt 3 devices. An important element to keep in mind is that the one functioning display connected to the dock is included in that total number.

The most simple (and least expensive) method to add two displays is to connect them directly to the Thunderbolt 3 ports of the system using a combination of any two of our USB-C video cables or adapters (one adapter for each display):

A slightly more expensive solution (but a one that requires the use of one less Thunderbolt 3 port) is to add one of our Thunderbolt 3 Dual Display Adapters:

Thunderbolt 3 Dual DisplayPort Adapter
Thunderbolt 3 Dual HDMI adapter

Thunderbolt 3 MacBook Pros with Intel GPU

Apple systems that have Thunderbolt 3 ports and have only an internal Intel graphics adapter (GPU) are slightly more limited, as they can only support a maximum of two external displays using a combination of USB-C or Thunderbolt 3 devices.

As mentioned earlier, the single video output of either dock that is still working counts against this total, so the only option is to add one additional display to the system using one of USB-C video cables or adapters:

Important Note—Thunderbolt 3 Dual Display adapters cannot circumvent the total display limitations present in any MacBook Pro. The total maximum number of displays will always be in effect regardless of what types of adapters or cables are in use. **

USB-C 12” Retina MacBook (no Thunderbolt 3 support)

For MacBooks (without the ‘Pro’ designation), as the system only has a single USB-C port unfortunately there are no other options to connect additional displays beyond what is already working in the dock. Without the ability to use a DisplayLink-powered device, the MacBook can only connect to one external display.

While certainly less than ideal, depending on what Mac system you have there are options to use more than the one additional display currently afforded by the dock. While certainly not a solution for the original problem caused by the update, these other connection types can provide at least a partial workaround.

Legacy MacBooks with Mini DisplayPort/Thunderbolt/Thunderbolt 2

We have not officially supported our USB 3.0 generation docking stations and graphics adapters on Mac due to driver issues present in OS X 10.9 (Mavericks) and later. But we realize that even though we state “Mac not supported” on these products, some customers did go ahead and purchase them for use on Mac systems. For these MacBooks, a Mini DisplayPort adapter can be used for a single display. Alternatively, Thunderbolt 2 docking stations are available from other vendors.

As always, please let us know if you have any questions in the comments below or contact us directly via

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