Updated 12/9/2016: This issue has been resolved in build 14986. If you are still running build 14971, update to the latest build to resolve this issue.
For anyone running the Insider Preview version of Windows 10 Enterprise, be advised that the latest Fast Ring build (14971) has a bug that breaks DirectAccess connectivity. Microsoft is aware of the issue and is currently working to identify the root cause. As it stands now, there is no known workaround.
I’ll post an update as soon as I have more information. Stay tuned!