I'm going to reiterate the comment someone else made: enable the debug mode. It can be very helpful with figuring out what is wrong. To enable debug mode, simply use the following line:

$ftp=Net::FTP->new("$host",Timeout=>240,Debug=>1) or die "connect\n";
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Also, I would recommend looking at the logs from the server you are attempting to connect to. If you do not have access to these logs, kindly ask your friendly neighborhood sysadmin to help you out.