.NET Downloading large file GetContentAsStreamAsync

I want to use the Dropbox. Api for .NET to allow my users to download files I have stores in Dropbox from my site.

The size of the files ranges from small (a few Mb) to Big (a couple of Hundred Mb)

This is the code I have:

public async void DownloadWithTracking(string argFilePath)
    {
        var aFileName = Path.GetFileName(argFilePath);
        
        using (var aDropboxClient = new DropboxClient(anAccessToken))
        {
            var aResponse = await aDropboxClient.Files.DownloadAsync(argFilePath);

            ulong aFileSize = aResponse.Response.Size;
            const int aBufferSize = 4 * 1024 * 1024;

            var aBuffer = new byte[aBufferSize];

            using (var aDropboxContentStream = await aResponse.GetContentAsStreamAsync())
            {
                Response.BufferOutput = false;
                Response.AddHeader("content-disposition", "attachment;filename=" + aFileName);
                Response.AddHeader("Content-Length", aFileSize.ToString());
                int aLengthOfBytesRead = aDropboxContentStream.Read(aBuffer, 0, aBufferSize);
                while (aLengthOfBytesRead > 0)
                {
                    Response.OutputStream.Write(aBuffer, 0, aLengthOfBytesRead);
                    aLengthOfBytesRead = aDropboxContentStream.Read(aBuffer, 0, aBufferSize);
                }
            }
        }
    }

If the files are small this code works perfectly but for the bigger files I get an error with this stackTrace:

System.IO.IOException was unhandled by user code
  HResult=-2146232800
  Message=The read operation failed, see inner exception.
  Source=System.Net.Http
  StackTrace:
       at System.Net.Http.HttpClientHandler.WebExceptionWrapperStream.Read(Byte[] buffer, Int32 offset, Int32 count)
       at System.Net.Http.DelegatingStream.Read(Byte[] buffer, Int32 offset, Int32 count)
       at test_DropboxTest.<DownloadWithTracking>d__0.MoveNext() in d:\Dropbox\NPC Website\website\test\DropboxTest.aspx.cs:line 41
  InnerException: System.Net.WebException
       HResult=-2146233079
       Message=The request was aborted: The request was canceled.
       Source=System
       StackTrace:
            at System.Net.ConnectStream.Read(Byte[] buffer, Int32 offset, Int32 size)
            at System.Net.Http.HttpClientHandler.WebExceptionWrapperStream.Read(Byte[] buffer, Int32 offset, Int32 count)
       InnerException: 

This happens after a few 10's of MB (from 20-50 Mb) 

Thanks in advance