Your error

Error executing run mode 'send_file': Cannot connect to host: Net::FTP
+: connect: timeout at /home/domains/xxx/www.xxx.com/aa/system/modules
+//FTP.pm line 16. at /home/domains/xxx/www.xxx.com/aa/index.cgi line 
+20
[download]

as well as the fact that it's happening 3/4 times makes me think that there's some sort of network connectivity issues. To isolate and confirm this,

• Run the command netstat -i from the linux box. (You can also run is netstat -aen on Windows 2k/XP/2k3). Does it give any errors? If so, it would be a problem not related to your code, e.g. bad network card, problem with the switch, etc.

• Try highering the timeout value - the default is 120, like so -

  use Carp;
  ....
  my $ftp = Net::FTP->new("XXX.XX.XX.XXX", Debug => 1, Port => 21, => Ti
  +meout => 300) or 
    croak "Cannot connect to host: $@";
  [download]

  Note that I used croak instead of die, which will give you more verbose information.

• You could also loop a couple times until you get a connection:

  my $ftp = Net::FTP->new("XXX.XX.XX.XXX", Debug => 1, Port => 21, => Ti
  +meout => 300);
  my $num_tries = 0;
  my $max_tries = 5 #you decide how many times you want to try
  
  while ( !$ftp) {
      if ($num_tries< $max_tries) ) {
           ++$num_tries;
           $ftp = Net::FTP->new("XXX.XX.XX.XXX", Debug => 1, Port => 21,
  + => Timeout => 300);
      } 
      if ($num_tries >= $max_tries) ) {    
           croak "Cannot connect to host, failed after $num_tries times 
  +: $@"; 
      }
  }
  [download]

• When it fails to connect, you could write code using Net::Ping to make sure it's up.