Announcing Windows 10 Insider Preview Build 14936 for PC and Mobile - Windows Blog

まっちゃん さん お知らせありがとうございます。

Authentication changes affecting connectivity to NAS devices and home file servers

After updating to the latest Insider Preview builds, you may have noticed that shared devices on your home network have disappeared from your home network folder. You may have also noticed your mapped network drives are not available. If you change your network to “private” or “enterprise”, it should start working again. For more information on this behavior change, see this Microsoft Security Bulletin.

よくわかんないけど、パブリック / プライベート の切り替えのおまじないをすれば動くよってことか…
# プライベートじゃなくて“enterprise”って表記もあるのか?