That's not a service error; there is a connection pool for each server that is limited to 50 connections. If there are already 50 people logged into FTP before you get there, you'll just have to try again later. I know that it can be frustrating when it happens to you, but server performance would be horrible otherwise -- doubling the number of simultaneous FTP sessions wouldn't change anything (considering the number of user account per server), and making it essentially unlimited would mean that HTTP would suffer.