405 Not Allowed through SSL - PHP Ajax Mailchimp API Nginx - php

Question

I've built a html web form that collects subscriber info through AJAX and process thru a php script, and send to mailchimp.
Form submission worked fine until SSL was added to the domain. I keep on getting 405 Not Allowed when I try to submit the form. And I couldn't figure out what went wrong. I have a feeling this has to do with the Nginx server configuration, but I'm no expert in this area and don't know where to look.
After some research, I came across a few posts discussing how 'Nginx does not allow POST to static content' which I'm not sure if it applies to my case because this issue only occurred after ssl was added (I'm using Nginx + php on Alicloud). Below are my codes:
<section id="mailchimp">
<div class="container">
<form id="form" method="POST" action="action.php">
<p class="sub-lead">* indicates required.</p>
<input type="email" name="EMAIL" id="form_email" placeholder="Email Address *" required="required">
<input type="text" name="FNAME" id="form_fname" placeholder="First Name *" required="required">
<input type="text" name="LNAME" id="form_lname" placeholder="Last Name *" required="required">
<input type="text" name="PHONE" id="form_phone" placeholder="Phone Number *" required="required">
<select name="ROOM" id="room">
<option value="" disabled selected>I am interested in...</option>
<option value="1 Bedroom">1 Bedroom</option>
<option value="2 Bedroom">2 Bedroom</option>
<option value="3 Bedroom">3 Bedroom</option>
</select>
<input type="checkbox" id="opt-in" name="opt-in" value="opt-in" required="required">Yes, I want to receive current & future projects info from the development team & its affiliates.<br>
<input type="submit" value="submit" id="submit">
<div id="signup-result"></div>
</form>
</div>
</section>
php
<?php
//fill in these values for with your own information
$api_key = 'xxxxxxxx-us16';
$datacenter = 'us16';
$list_id = 'xxxxxxxxx;
$email = $_POST['email'];
$fname = $_POST['first_name'];
$lname = $_POST['last_name'];
$phone = $_POST['phone'];
$room = $_POST['room'];
$country = $_POST['country'];
$status = 'subscribed';
if(!empty($_POST['status'])){
$status = $_POST['status'];
}
$url = 'https://'.$datacenter.'.api.mailchimp.com/3.0/lists/'.$list_id.'/members/';
$username = 'apikey';
$password = $api_key;
$data = array("email_address" => $email,
"status" => $status,
"merge_fields" => array(
"FNAME" => $fname,
"LNAME" => $lname,
"PHONE" => $phone,
"ROOM" => $room,
)
);
$data_string = json_encode($data);
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
curl_setopt($ch, CURLOPT_USERPWD, "$username:$api_key");
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
'Content-Type: application/json',
'Content-Length: ' . strlen($data_string))
);
$result=curl_exec ($ch);
curl_close ($ch);
echo $result;
?>
here's the ajax
// Mailchimp Form
$('#form').submit(function(e){
e.preventDefault();
//grab attributes and values out of the Form
var data = {
email: $('#form_email').val(),
first_name: $('#form_fname').val(),
last_name: $('#form_lname').val(),
phone: $('#form_phone').val(),
room: $('#room').val(),
};
var endpoint = $(this).attr('action');
//make the ajax request
$.ajax({
method: 'POST',
dataType: "json",
url: endpoint,
data: data
}).done(function(data){
if(data.id){
//successful adds will have an id attribute on the object
window.location='thankyou.html'
} else if (data.title == 'Member Exists') {
//MC wil send back an error object with "Member Exists" as the title
alert('It looks like you have already signed up with this email address. If you have any questions, please feel free to contact us by email or phone.');
} else {
//something went wrong with the API call
alert('Oops, we could not reach server at the moment, please try again later.');
}
}).fail(function(){
//the AJAX function returned a non-200, probably a server problem
alert('oh no, there has been a problem');
});
});