It seems it is a hard-limit that the maximum file size that can be uploaded is 2GB using HTTP POST with ASP.Net.
https://blogs.msdn.microsoft.com/friis/2013/06/19/uploading-large-file-to-iis-7-5-or-8-using-file-input-element/
I'll need to devise a way to exceed this limit.
There are other protocols: ftp, ssh, etc. that may be able to be leveraged.