Timeout with socket io - node.js

Question

I have an application using socket.io with Node and Express. I'm also using AWS EC2 and Nginx.
I'm getting a timeout with socket io.
The error is:
GET https://vusgroup.com/socket.io/?EIO=3&transport=polling&t=MnUHunS 504 (Gateway Time-out)
Express file:
var port = 8090;
host = 'https://18.237.109.96'
var app = express(host);
var webServer = http.createServer(app);
...
// Start Socket.io so it attaches itself to Express server
var socketServer = socketIo.listen(webServer, {"log level":1});
//listen on port
webServer.listen(port, function () {
console.log('listening on http://localhost:' + port);
});
Nginx file:
server {
listen 80 default_server;
listen [::]:80 default_server;
location / {
# First attempt to serve request as file, then
# as directory, then fall back to displaying a 404.
proxy_pass http://18.237.109.96:8090/;
}
}
server {
server_name vusgroup.com www.vusgroup.com; # managed by Certbot
listen [::]:443 ssl ipv6only=on; # managed by Certbot
listen 443 ssl; # managed by Certbot
...
ssl stuff
...
location / {
# First attempt to serve request as file, then
# as directory, then fall back to displaying a 404.
proxy_pass http://18.237.109.96:8090/;
}
location /socket.io/ {
proxy_pass http://18.237.109.96:3000;
proxy_redirect off;
proxy_http_version 1.1;
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;
}
}
I've tried chaning the proxypass for socket.io to http://18.237.109.96:8090; but that gave me a 400 error.