Hello, I would recommend getting the firefox add-on Firebug, inspect the page for the form's name in the HTML, and add it that way. for example:

$mech->submit_form (
form_name => 'form',
fields => { modem => '1122.3344.5566',
ip_select => '1.2.3.4'}
);
[download]

In fact, looking at your code again to give you that example, problems may have been caused by not separating the field names with a comma? But I'm not sure.. see if that works for you, though..