Express and NodeJS page loading forever

I am simply trying to run the express-generator app on a webserver but when I try to access it I either get a 304 cache response or the page just loads forever. The headers of my requests look like this:

  HTTP/1.1 200 OK
    X-Powered-By: Express
    Content-Type: text/html; charset=utf-8
    Content-Length: 2290
    ETag: W/"8f2-7nlqOssTFqOeU1h/YgwrQulUCxQ"
    Date: Wed, 15 Mar 2017 12:04:48 GMT
    Connection: keep-alive

and according to redbot.org:

General

    The server's clock is 12 sec ahead.
    The Content-Length header is correct.

Caching

    This response allows all caches to store it.
    This response allows a cache to assign its own freshness lifetime.

Validation (ETag Validation response - 1 problem )

    If-None-Match conditional requests are supported.

The NodeJS code is the base express-generator code I have literally changed nothing.

What could be the issue ?

via Rémi