Amazon FSx for Windows File Server with SMB and AWS Client VPN is the correct choice because it provides a fully managed SMB file system that integrates with Active Directory and supports standard file semantics. Corporate applications can mount the same shared storage and remote employees can connect securely by using AWS Client VPN.

Amazon FSx for Windows File Server with SMB and AWS Client VPN offers high availability and native SMB protocol support which preserves file locks and permissions and enables applications that expect a traditional file server to work without modification. The Client VPN component provides secure, client based connectivity so employees working from different countries can access the same file share as if they were on the corporate network.

AWS DataSync is designed for fast data transfer and migration between on premises storage and AWS and it does not provide a persistent, mountable SMB endpoint for simultaneous access by users and applications.

Amazon WorkDocs is a document collaboration service for end users and it does not expose an SMB file share that line of business applications can mount in the same way as a network file server.

AWS Storage Gateway volume gateway exposes iSCSI block volumes rather than SMB or NFS file shares and it is therefore not suited for widely distributed users who need a managed SMB share with standard file semantics.

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