Thanks. I submitted the form. In the troubleshot, I see this item
The server where your Moodle site is installed is able to connect to messages.moodle.net (port 443) via telnet
How can I test that? This is what I get
mahmood@ce:~$ telnet messages.moodle.net 443
Trying 34.248.225.86...
Connected to alb-production-83366492.eu-west-1.elb.amazonaws.com.
Escape character is '^]'.
help
HTTP/1.1 400 Bad Request
Server: awselb/2.0
Date: Thu, 17 May 2018 06:45:51 GMT
Content-Type: text/html
Content-Length: 138
Connection: close
<html>
<head><title>400 Bad Request</title></head>
<body bgcolor="white">
<center><h1>400 Bad Request</h1></center>
</body>
</html>
Connection closed by foreign host.
mahmood@ce:~$