php - Facebook SDK returned an error: Connection timed out after 10001 milliseconds -

i have integrated facebook login (php sdk version 5.0.0) website. working fine in localhost. shows following error when have hosted in server;

facebook sdk returned error: connection timed out after 10001 milliseconds

i have changed 'site url' , 'oauth redirect uri' when hosted in server. necessary change else in app? have checked curl enabled in server, showing 'enabled' in php ini. php version 5.5.28.

my code given below;

index.php:

<?php session_start(); error_reporting(e_all);  $path = realpath(dirname(__file__));  require $path .'/facebook-sdk-v5/autoload.php';  $fb = new facebook\facebook([     'app_id' => 'xxxxxxx',     'app_secret' => 'xxxxxxxx',     'default_graph_version' => 'v2.4',         ]);  $helper = $fb->getcanvashelper();  // grab signed request entity $sr = $helper->getsignedrequest();  // user id if signed request exists $user = $sr ? $sr->getuserid() : null;  if ($user) {     try     {         // access token         $accesstoken = $helper->getaccesstoken();     }     catch (facebook\exceptions\facebooksdkexception $e)     {         // there error communicating graph         echo $e->getmessage();         exit;     } } else {     $helper = $fb->getredirectloginhelper();      $permissions = ['public_profile','email','user_birthday','user_location']; // optional     $callback = 'http://www.example.com/ret_page.php';     $loginurl = $helper->getloginurl($callback, $permissions);      echo '<a href="' . $loginurl . '">log in facebook!</a>';   } 

ret_page.php:

<?php session_start(); error_reporting(e_all);  $path = realpath(dirname(__file__)); require $path .'/facebook-sdk-v5/autoload.php';  $fb = new facebook\facebook([     'app_id' => 'xxxxxx',     'app_secret' => 'xxxxxxxxxxx',     'default_graph_version' => 'v2.4',         ]);  $helper = $fb->getredirectloginhelper();  try {     $accesstoken = $helper->getaccesstoken(); } catch (facebook\exceptions\facebookresponseexception $e) {     // when graph returns error     echo 'graph returned error: ' . $e->getmessage();     exit; } catch (facebook\exceptions\facebooksdkexception $e) {     // when validation fails or other local issues     echo 'facebook sdk returned error: ' . $e->getmessage();     exit; }  if (!isset($accesstoken)) {     if ($helper->geterror())     {         header('http/1.0 401 unauthorized');         echo "error: " . $helper->geterror() . "\n";         echo "error code: " . $helper->geterrorcode() . "\n";         echo "error reason: " . $helper->geterrorreason() . "\n";         echo "error description: " . $helper->geterrordescription() . "\n";     }     else     {         header('http/1.0 400 bad request');         echo 'bad request';     }     exit; }  // logged in echo '<h3>access token</h3>'; var_dump($accesstoken->getvalue());  $fb->setdefaultaccesstoken($accesstoken); $res    = $fb->get('/me?fields=id,name,gender,email,birthday,location'); $user   = $res->getgraphobject();  // printing result print_r($user);