Streamed response from laravel to android

Question

On our platform (based on Laravel 5.1) we provide audio and video content to registered users. The media files are stored outside the docroot of course.

So I use a method to provide the requested content. That works well on any browser and OS except Android (native or chrome). Android uses a byte range request for audio and video tags. The following code worked in the beginning and stopped working a while ago. I have no clue why. Any:

public function loadfile(Request $request, $type, $filename="")
{


    $filepath = $mediadirectory . $filename;

    if (File::isFile($filepath)) {
        $file = File::get($filepath);
        $mimetype = File::mimeType($filepath);
        $size = File::size($filepath);
        if ($mimetype=="audio/mpeg" || $mimetype=="video/mp4") {
            $stream = fopen($filepath, "r");
            $start = 0;
            $length = $size;
            $status = 200;

            $headers = ['Content-Type' => $mimetype, 'Content-Length' => $size, 'Accept-Ranges' => 'bytes'];

            if (false !== $range = $request->server('HTTP_RANGE', false)) {
                list($param, $range) = explode('=', $range);
                if (strtolower(trim($param)) !== 'bytes') {
                    header('HTTP/1.1 400 Invalid Request');
                    exit;
                }
                list($from, $to) = explode('-', $range);
                if ($from === '') {
                    $end = $size - 1;
                    $start = $end - intval($from);
                } elseif ($to === '') {
                    $start = intval($from);
                    $end = $size - 1;
                } else {
                    $start = intval($from);
                    $end = intval($to);
                }
                $length = $end - $start + 1;
                $status = 206;
                $headers['Content-Range'] = sprintf('bytes %d-%d/%d', $start, $end, $size);
                $headers['Connection'] = "keep-alive";
            }
            $response=new StreamedResponse(function() use ($stream, $start, $length) {
                fseek($stream, $start, SEEK_SET);
                echo fread($stream, $length);
                fclose($stream);
            }, $status, $headers);
            return $response->send();

        } else {
            return response($file, 200)->header('Content-Type', $mimetype)->header('Content-Length', $size)->header('Content-Disposition', 'filename="' . $filename . '"');
        }
    }

}

The html is straight forward html5:

<audio controls preload="auto">
    <source src="/loadfile/principiante.mp3" type="audio/mpeg">
</audio>