You may see one of the following errors after a particularly large deployment, which has caused your server to time out.
Error communicating with your server: Net::ReadTimeout
Connection timed out
If you're using FTP to connect, it may be worth switching to SSH/SFTP instead as this will give you a much faster and more reliable connection.
If possible you should contact your server host to obtain some FTP logs as this should provide additional information.
This could also be caused by a firewall configuration issue. You will need to allow our IP addresses through your firewall.