Nginx reverse proxy causing 504 Gateway Timeout

I am using Nginx as a reverse proxy that takes requests then does a proxy_pass to get the actual web application from the upstream server running on port 8001.

If I go to mywebsite.com or do a wget, I get a 504 Gateway Timeout after 60 seconds… However, if I load mywebsite.com:8001, the application loads as expected!

So something is preventing Nginx from communicating with the upstream server.

All this started after my hosting company reset the machine my stuff was running on, prior to that no issues whatsoever.

Here's my vhosts server block:

server {
    listen   80;
    server_name mywebsite.com;

    root /home/user/public_html/mywebsite.com/public;

    access_log /home/user/public_html/mywebsite.com/log/access.log upstreamlog;
    error_log /home/user/public_html/mywebsite.com/log/error.log;

    location / {
        proxy_pass http://xxx.xxx.xxx.xxx:8001;
        proxy_redirect off;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
} 

And the output from my Nginx error log:

2014/06/27 13:10:58 [error] 31406#0: *1 upstream timed out (110: Connection timed out) while connecting to upstream, client: xxx.xx.xxx.xxx, server: mywebsite.com, request: "GET / HTTP/1.1", upstream: "http://xxx.xxx.xxx.xxx:8001/", host: "mywebsite.com"