如何在HTTPS上修复Soap解析WSDL错误？

I'm trying to get some data from a remote server with SOAP using PHP 7.0, but I get the following error:

SoapFault Object[message:protected] => SOAP-ERROR: Parsing WSDL: Couldn't load from 'https://url.com'.

It works fine on the browser and when https is disabled.

I've already tried to disable SSL verification with:

 'ssl' => [
        // set some SSL/TLS specific options
        'verify_peer' => false,
        'verify_peer_name' => false,
        'allow_self_signed' => true
    ]

And to pass my cert and key with:

  'ssl' => [
        'local_cert' => $sslClientCert,
        'local_pk' =>  $sslClientKey'
    ]

None of them works. I have also verified that openssl is enabled on the server with phpinfo(). How do I solve this problem?

Attempt

<?php

$url = "https://theurl.com";
$client = new SoapClient($url, [
        'stream_context' => stream_context_create([
        'ssl' => [
             "verify_peer"=>false,
             "verify_peer_name"=>false,
            ]
        ]),
        'trace' => 1,
        'exceptions' => true
    ]);

    $params = ['groups' => [
        [
            "courseid" => 3,
            "name" => "Group test",
            "description" => "Group test",
            "descriptionformat" => 1,
            "enrolmentkey" => "",
            "idnumber" => ""
        ]
    ]];

   $response = $client->__soapCall('core_group_create_groups',$params);