Site is being load balanced and you get this error is different locations:

It works!

This is the default web page for this server.

The web server software is running but no content has been added, yet.

This is using apache vs Nginx.

Restart nginx fails:

root@web2:/var/log/nginx# tail -f error.log
2015/09/11 01:00:13 [emerg] 5190#5190: bind() to [::]:80 failed (98: Address already in use)
2015/09/11 01:00:13 [emerg] 5190#5190: bind() to 0.0.0.0:80 failed (98: Address already in use)

Then it means nginx or some other process is already using port 80.

You can kill it using:

# sudo fuser -k 80/tcp

And then try restarting nginx again:

# service nginx start