Issue NodeJS simple app runs but Express JS does not

[lukegalea16]

When running a simple app.js file on my subdomain which serves a web page on port 3000 everything loads fine. When I upload an Express JS application which also serves a web page on port 3000 I get a 504 nginx gate way timeout. What could the issue be?
In my logs I get this error:

1683889#0: *13263 upstream timed out (110: Connection timed out) while reading response header from upstream