Can't upload large file over SFTP (SshOperationTimeoutException)

Bắt đầu với đường đi của stack trace qua SftpClient.InternalUploadFile, SftpSession.RequestWrite, Channel.SendData và Session.WaitOnHandle. Tái hiện một lần tải lên SFTP lớn với thời lượng gần với thời lượng được báo cáo và xác định lý do session timeout xảy ra; hoàn thành có nghĩa là quá trình truyền hoàn tất mà không bị timeout và hành vi này được bao phủ bởi một regression test phù hợp.

For uploading .csv file over SFTP I use SSH.NET (version 2016.0.0).

The file which needs to be send is rather large (~7GB), and in about an hour after the uploading started it throws the exception Renci.SshNet.Common.SshOperationTimeoutException: Session operation has timed out.

Here is my actual uploading code.

using (SftpClient client = new SftpClient(command.FtpHost, command.UserName, command.Password))
{
    client.Connect();
    client.ChangeDirectory(command.FtpTargetFolder);

    // played a lot with BufferSize property
    // tried to use the default value, tried 4*1024 and 8*1024
    client.BufferSize = 2 * 1024; 

    using (FileStream fileStream = new FileStream(command.LocalFilePath, FileMode.Open))
    {
        client.UploadFile(fileStream, PrepareFileName(command.LocalFilePath));
    }
    client.Disconnect();
}

But this code works fine with smaller (tried with 1-4GB files) files than my desirable one (~7GB). I thought that it could depends on BufferSize, but playing with this property didn't fix the problem.

Here is the issue's stack trace.

Renci.SshNet.Common.SshOperationTimeoutException: Session operation has timed out
at Renci.SshNet.Session.WaitOnHandle(WaitHandle waitHandle, TimeSpan timeout)
at Renci.SshNet.Channels.Channel.GetDataLengthThatCanBeSentInMessage(Int32 messageLength)
at Renci.SshNet.Channels.Channel.SendData(Byte[] data, Int32 offset, Int32 size)
at Renci.SshNet.Sftp.SftpSession.SendRequest(SftpRequest request)
at Renci.SshNet.Sftp.SftpSession.RequestWrite(Byte[] handle, UInt64 offset, Byte[] data, Int32 length, AutoResetEvent wait, Action'1 writeCompleted)
at Renci.SshNet.SftpClient.InternalUploadFile(Stream input, String path, Flags flags, SftpUploadAsyncResult asyncResult, Action'1 uploadCallback)

Also I've noticed that usually uploading throws the error in 1 hour after start and by that time it's uploaded ~80-90% of entire file (because I see not fully uploaded files in my destination SFTP folder).

Does someone has an idea why it's happening?
Btw I've asked StackOverflow question regarding that: http://stackoverflow.com/questions/40158501/cant-upload-large-file-over-sftp
Thanks in advance.