While the latest version of MacOS may give external GPU support, it has apparently also broke DiaplayLink protocol support, rendering thousands of monitors dead. DisplayLink themselves have stated that High Sierra 10.13,4 will cause DisplayLink connected displays to go blank, and they have alerted Apple of the issue, and are working to find a resolution. More worrying though is a post on the DisplayLink forums, where the user of a "Pluggable Triple Display Docking Station" posted a message from the manufacturer that may indicate that this is a permanent change to MacOS going forward. The manufacturer states: This new macOS release only supports displays which are directly provided by a GPU or via AirPlay. For this dock, this means versions of Apple macOS after 10.13.3 will only support the single 4K HDMI port on the dock which uses DisplayPort Over USB-C technology (which is directly GPU connected). The second and third displays on the dock -- the DVI and 2K HDMI ports using DisplayLink technology -- will no longer function. Nice job Apple. DisplayLink as well as the dock manufacturer quoted above state that if you intend to use a DisplayPort monitor, do not upgrade to 10.13.4.