Connection closed during file upload - ELB timeout?

We recently moved a Nexus instance to AWS and are having trouble with large file uploads being closed. We suspect this may be due to the ELB timeout due to this gem:

"If an HTTP request doesn't complete within the idle timeout period, the load balancer closes the connection, even if data is still being transferred. "

Source: http://ift.tt/1KyGFJY

How can a connection be idle if it is transferring data?? Why would it be done this way?

Some of the files are many gigabytes - it may take several minutes to upload, let's say 30 minutes if busy. How are we supposed to support this, is setting the timeout to 1800s really the recommended fix? (max 3,600)

Thanks, Joel