After announcing last June that Windows Server 2016 will also have his own Insider program and builds, Microsoft has released the first Windows Insider build (build 16237).
As for Windows 10, Preview builds are not aimed to be production ready, so you may expect some glitch.
To start running your own Windows Server preview you need first to register to the Windows Insider for Business program here or to the Windows Insider program one here.
As part of this first Insider build, you have:
Details are available here https://blogs-windows-com.cdn.ampproject.org/c/s/blogs.windows.com/windowsexperience/2017/07/13/announcing-windows-server-insider-preview-build-16237/amp/
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