All you need for transfering files over the Internet: FTP, FTP over TLS/SSL, SFTP (SSH Secure File Transfer Protocol), File Server.
(trial binaries and samples for .NET 2.0-4.8, .NET Core/.NET Standard, .NET CF 3.5-3.9, Mono, Xamarin.iOS, Xamarin.Android)
(trial binaries and samples for .NET 2.0-4.8, .NET Core/.NET Standard, .NET CF 3.5-3.9, Mono, Xamarin.iOS, Xamarin.Android)
Packages for OS X and Linux