I can't see why your script behaves differently when you put the login parameters in a different module but in any case, instead of mixing them all in one string, you can pass then to Net::OpenSSH as different arguments:

my $ssh = Net::OpenSSH->new($host,
                            user => $user,
                            password => $password,
                            timeout => 10);
[download]

You can also activate debugging in order to see what is going on:

$Net::OpenSSH::debug = -1;
[download]