due to some security issues (Wannacry) Windows administrators are going to disable the unsecure smb1 protocol.
mount.cifs is using smb1 by default. So when you tried to connect to a Windows machine where smb1 is disabled you get an error: mount error(112): Host is down.
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since some later Versions of Windows 10 it is no longer possible to access Samba Public shares with Guest access as Windows User SYSTEM(i.e. from Schedule Tasks).
The error occured is:
The specified server cannot perform the requested operation.