There are reports that the latest version of macOS High Sierra 10.13.4 breaks support for many externally connected displays. Devices from DisplayLink, Duet Display, Air Display, and iDisplay are impacted. Apparently the displays go black after installing the update. Other monitor features such as Ethernet and audio are not impacted. For now, the manufacturers are recommending to remain at macOS 10.13.3. I'm pretty sure staying with an older vulnerable operating system is not a sound recommendation. I would suggest forgoing the external display (or getting a different manufacturer) until a fix is available.
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Digital Forensics/Information Security/Information Technology