We are facing an issue with downloading files from _every_ target system with the constant speed of exactly 8 KB per second. Never less, never more. This is what the progress bar shows in the File Access module. It also doesnt matter which target operating system is used or where they are gepgraphically located. Also file sizes dont matter - can be 500KB or 20MB. 
The FS Master server allows a higher speed.

FS 4.50

Engineer Alex H. also tested it with the your demo server and randomly came to the same result. Partially it was downloaded in a heartbeat, partially also just wiht 8kb / sec.

Ideas would be highly appreciated.