OpenSSL SSL_read： SSL_ERROR_SYSCALL， errno 104

我通过curl在基于ssl means（https）的api上放置订单数据，但它返回OpenSSL SSL_read：SSL_ERROR_SYSCALL，errno 104消息。

以下是我的测试代码，根据客户端所需的json：

$apiKey = "xxxxxx-xxxxxx-xxxxx-xxxxxx-xxxxxx";
$privatekey = "xxxxxx-xxxxxx-xxxxx-xxxxxx-xxxxxx";
$timestamp = date('Y-m-d H:i:s'); // (for example: 2016-07-19 14:05:55)

$signature = hash_hmac('sha1', $timestamp, $apiKey);
$signature = hash_hmac('sha1', $privatekey, $signature);

$postURL = "https://www.compu-cover.com/intelligent-rewards/orders/?OrderNo=123";

$orderInfo['Order'] = array(
        "apiKey" => $apiKey,
        "privatekey" => $privatekey,
        "Signature" => $signature,
        "Timestamp" => $timestamp,
        "Firstname" => "Ajay",
        "Surname" => "Sharma",
        "EmailAddress" => "ajay@yopmail.com",
        "DaytimeTel" => "0141798526",
        "EveningTel" => "0141798526",
        "MobileTel" => "9887654321",
        "Address1" => "A-5",
        "Address2" => "Jhalana",
        "Address3" => "Jaipur",
        "Address4" => "Rajasthan",
        "County" => "India",
        "Postcode" => "302019", 
        "Cover" => "ADTBL",
        "Scheme" => 2, 
        "Premium" => 5,
        "EquipmentQty" => 1,
        "EquipmentType1" => "Smartphone",
        "EquipmentMake1" => "Moto",
        "EquipmentModel1" => "Moto G",
        "EquipmentPrice1" => 100
    );

$params = json_encode($orderInfo);

$session = curl_init($postURL);

curl_setopt($session, CURLOPT_POST, true);
curl_setopt($session, CURLOPT_POSTFIELDS, $params);
curl_setopt($session, CURLOPT_HEADER, true);
curl_setopt($session, CURLOPT_SSL_VERIFYPEER, true); 

$response = curl_exec($session);

if (FALSE === $response) {
    var_dump(curl_error($session));
    var_dump(curl_errno($session));
}

curl_close($session);
$response = json_decode($response);

var_dump($response);

如何找到失败的原因？失败的原因可能是什么？请提供您的建议。