We are getting random backup fails, never the same virtual server and not everyday and not always on the same server.
Uploading archive to Amazon's S3 service ..
.. upload failed! Empty response to HTTP request. Headers were :
.. completed in 9 minutes, 47 seconds
Have set "Number of times to re-try FTP or S3 uploads" to 10 as per other Issues and that reduced the number of fails but has not completely resolved the issue.