WebDAV is also on my list. Seems to me it's more directly focused on remote file access rather than VPN's private browsing focus. There are just so many different options. I was hoping for some clarification what does what.
File sharing: SMB vs. FTP vs. WebDAV - Ars Technica OpenForum Sep 30, 2003 Which file access is the best : Webdav or FTP? - Stack SFTP is more feature-rich than WebDAV and SFTP is a protocol to access remote file systems, while WebDAV was designed with abstraction in mind (WebDAV was for "documents", while SFTP is for files and directories). SFTP has all benefits mentioned above for WebDAV and is more popular among both admins and developers.
File sharing: SMB vs. FTP vs. WebDAV - Ars Technica OpenForum
The following details how to setup WebDAV to access your files securely on a Synology Network Attached Storage device and be able to map it as a network drive. This means that over the Internet, you can access your Synology device as a mapped drive. This method is free and also provides a secure mapped drive connection
시놀로지 NAS서버 WebDav 설정을 통한 네트워크 드라이브 연결하기 …
Is it still a bad idea to run SMB over the internet? - Ars