Help resolving 'site can't be reached' on express route with nodejs and passport js

I’ve been trying to deploy my web app the past few days, and while I can reach my site, when I try to navigate to an express route activated by a login button it gives me ‘localhost refused to connect’. My pages are served on localhost:3000, and my passport authentication and mongodb requests are made on port 4000.

Here is my /etc/nginx/sites-available/default

server {

        root /var/www/html;

        # Add index.php to the list if you are using PHP
        index index.html index.htm index.nginx-debian.html;

        server_name <my_url> www.<my_url>;

        location ^~ /assets/ {
                gzip_static on;
                expires 12h;
                add_header Cache-Control public;
        }

        location / {
                proxy_http_version 1.1;
                proxy_cache_bypass $http_upgrade;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection 'upgrade';
                proxy_set_header Host $host;
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header X-Forwarded-Proto $scheme;

                proxy_pass http://localhost:3000;
        }
        location /Notes {
                proxy_pass http://localhost:4000;
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection 'upgrade';
                proxy_set_header Host $host;
                proxy_cache_bypass $http_upgrade;
        }
    listen [::]:443 ssl ipv6only=on; # managed by Certbot
    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/<my_url>/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/<my_url>/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot

}

server {
    if ($host = <my_url>) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


        listen 80 default_server;
        listen [::]:80 default_server;

        server_name <my_url> www.<my_url>;
    return 404; # managed by Certbot


}

My routes are defined below, I’ve only included a few for brevity.

let PORT = 4000;

mongoose.connect('mongodb://localhost:27017/Notes', { dbName: "notes", useNewUrlParser: true>
const connection = mongoose.connection;

app.route('/Notes/auth/google').get( async (req, res, next) => {
    passport.authenticate('google', {scope: ['profile']})(req, res, next);
});

app.use(cors({credentials: true, origin: 'http://localhost:3000'}));
app.use("/",noteRoutes);
app.use('/Notes/loggedin', async (req, res) => {
    res.send(req.user);
});
app.listen(PORT, function(){
    console.log(`Server is running on port ${PORT}`);
    //console.log(app._router.stack);
});

My setup works great on localhost running on my own machine, but after deployment I cannot for the life of me get the redirect working. I am fairly certan I have the passport authentication setup correctly with the google API configured.

I’ve tried a few different configurations of the /etc/nginx/sites-available/default file, and haven’t had any luck, though I’m not sure I am understanding it properly. Port 4000 has been allowed with ufw.

Any help/suggestions would be extermely helpful, thank you!!