$ curl -A Twitterbot http://staging.microduino.cc/discover
<html>
<head><title>502 Bad Gateway</title></head>
<body bgcolor="white">
<center><h1>502 Bad Gateway</h1></center>
<hr><center>nginx/1.9.15</center>
</body>
</html>
You’ll need to resolve that issue before the crawler can work.