All pages return the same content with OVH Cloud Hosting

I've recently completed a Node.js website locally, which works fine, though I have noticed some issues when uploading the website online to OVH Cloud Web Hosting. All pages, even those that should not exist, return the contents of the homepage.

I'm running Express with Node.js, and the file structure was created with express-generator. My app.js file contains the following:

var indexRouter = require('./routes/index');
var blogRouter = require('./routes/blog');
var blogItemRouter = require('./routes/blog-item');
var portfolioRouter = require('./routes/portfolio');
var contactRouter = require('./routes/contact');
var iBlogPostsRouter = require('./routes/i/blog-posts');
var iContactRouter = require('./routes/i/contact');
var iPortfolioItemsRouter = require('./routes/i/portfolio-items');
var portfolioItemRouter = require('./routes/portfolio-item');

app.engine('.hbs', expressHbs({defaultLayout: 'layout', extname: '.hbs'}));
app.set('view engine', '.hbs');
app.disable('etag');

app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

app.use('/', indexRouter);
app.use('/blog', blogRouter);
app.use('/blog/:title', blogItemRouter);
app.use('/portfolio', portfolioRouter);
app.use('/contact', contactRouter);
app.use('/i/blog-posts', iBlogPostsRouter);
app.use('/i/contact', iContactRouter);
app.use('/i/portfolio-items', iPortfolioItemsRouter);
app.use('/portfolio/:title', portfolioItemRouter);

app.use(function(req, res, next) {
    next(createError(404));
});

app.use(function(err, req, res, next) {
    res.status(err.status || 500);
    res.render('error', {title: err.status + ' ' + err.message});
});

All of the routers have the same code, except render a different template. Here is an example of the indexRouter:

router.get('/', function(req, res, next) {
  res.render('index', { title: 'About', about: true });
});

The issue is that every page, even my .js and .css files, returns the HTML from whatever is in the app.use('/' ...) router. The console returns the following error:

Resource interpreted as Stylesheet but transferred with MIME type text/html: "https://reesmorris.co.uk/core/styles/m.css".

I experimented with this by changing the homepage to be my contact page, which has resulted in every URL returning the contact page. My CSS and JavaScript are in a public folder. The only thing that I can think of is that the '/' route is somehow being used for every single request, but it doesn't make any sense to me why this could be happening.

You can view the website here as I know it can be easier to understand if you can actually see it. Thanks in advance.

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