Unable to receive response after sending request with Guzzle - php

Question

I have a simple POST request using Guzzle from Laravel to send. I tested the request with Postman but it keeps sending request until timeout without returning any response data. I set up some URLs to return sample data and they work fine when testing separately. But when bring the URLs to the request to call from Guzzle, then this sending-request-till-forever happened. Hope you guys can help me shed some light on this problem.
Here is my request code:
$client = new Client();
$req = new Request('POST', 'http://13.114.233.87/api/ocr');
$reqData = $client->send($req, ['timeout' => 5]);
return $reqData;
Here are the handlers for each sample URL:
(1) http://13.114.233.87/api/ocr
Route::post('ocr', 'OcrController#postOcrData'); // routing
public function postOcrData()
{
return response()->json(collect([
'request_id' => rand(0, 9),
'result' => 0,
'error_code' => '',
'error_message' => ''
]));
}
(2) http://13.114.233.87/api/ocr/getResult/{id}
Route::get('ocr/getResult/{id}', 'OcrController#getOcrData'); // routing
public function getOcrData($id)
{
return response()->json(collect([
'request_id' => $id,
'result' => 0,
'error_code' => '',
'error_message' => '',
'fields' => []
]));
}