How to send Push Notification to multiple devices?

I found that you have to create a new stream_context_create for each fwrite to prevent apple from closing the connection for a bad token.

Try this example code and modify for your environment.

    $apnsHost = '<APNS host>';
    $apnsPort = <port num>;
    $apnsCert = '<cert>';

    $streamContext = stream_context_create();
    stream_context_set_option($streamContext, 'ssl', 'local_cert', $apnsCert);

    $apns = stream_socket_client('ssl://' . $apnsHost . ':' . $apnsPort, $error, $errorString, 60, STREAM_CLIENT_CONNECT, $streamContext);

    $payload['aps'] = array('alert' => 'some notification', 'badge' => 0, 'sound' => 'none');
    $payload = json_encode($payload);

// Note: $device_tokens_array has list of 5 devices' tokens

    for($i=0; $i<5; $i++)
    {
            $apnsMessage = chr(0) . chr(0) . chr(32) . pack('H*', str_replace(' ', '', $device_tokens_array[i])) . chr(0) . chr(strlen($payload)) . $payload;

            fwrite($apns, $apnsMessage);
    }?>

This article helps verifying drop connection and connection status: Apple Push Notification: Sending high volumes of messages

Other reference links:

How can I send push notification to multiple devices in one go in iPhone? and how to handle multiple devices when using Push Notification?