There is a case when your hosting provider (110mb.com being one of the examples) doesn’t allow more than 1 simultaneous connection per user for file transfers using FTP as it will be restricted from their FTP server due to some security reasons.
And if you are using Filezilla, then by default it will try to connect multiple FTP connections. It can connect maximum 11 connections i.e. 10 connections (simultaneous file transfer) +1 (browse the server files) per tab. If it is more than 11 simultaneous connections then either router, firewall or ftp server is compromised. You should report to your hosting provider or site admin.