My first question would be what happens if you try to connect to the same host with a command-line SSH client?

I've recently started using Net::SSH::Perl myself (so I'm no expert), but you might try setting one or more of the following options when creating the object:

  options => [ 
      q{BatchMode yes}, 
      q{ConnectTimeout } . $connect_timeout_in_sec, 
      q{TCPKeepAlive yes}, 
  ],
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Also, you might try wrapping your $ssh->cmd() call in an eval() and checking to see if it completes successfully or not (perhaps similar to the following):

    eval { ( $stdout, $stderr, $exit ) = $ssh->cmd($cmd); };

    if ($@) {
        # Do something as a result
    }
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Hope that helps. (And if you find an answer that helps, I'd love to see it as an update or reply.)