Node Socketio Websocket on Subdomain - node.js

Question

Since weeks I am trying to implement my websocket functionality on my production (ubuntu) Server (nginx). My websockets work locally, but I Keep getting Errors on production.
My socket.js Looks like this:
var fs = require('fs');
var options = {
type: "local",
key: fs.readFileSync("/etc/nginx/ssl/sub.domain.com/467605/server.key"),
cert: fs.readFileSync("/etc/nginx/ssl/sub.domain.com/467605/server.crt")
};
if (options.type == 'dev') {
var app = require('http').createServer(handler);
} else {
var app = require('http').createServer(options,handler);
}
var io = require('socket.io')(app);
var Redis = require('ioredis');
var redis = new Redis();
function handler(req, res) {
res.writeHead(200);
res.end('');
}
io.on('connection', function(socket) {});
// Redis UserSignedUp Channel, Channel if user signs up
var redisUserSignedUp = new Redis();
redisUserSignedUp.subscribe('signed-up-channel');
redisUserSignedUp.on('message', function(channel, message) {
message = JSON.parse(message);
io.emit(channel + ':' + message.event, message.data);
});
// run server on port 3333
app.listen(3333, function () {
console.log('Server running!');
});
My Event.js Looks like this:
const socket = io('sub.domain.com:3333', {
secure: true
});
// ... works locally
socket.on('signed-in-channel:App\\Events\\UserSignedIn', (data) => {
this.signedInUsers = data.username;
this.$toasted.info('Success: ' + data.username, {
theme: "primary",
duration: 10000
});
});
If I do this in my Event.js:
const socket = io('sub.domain.com:3333', { secure: true });
I get this error:
https://sub.domain.com:3000/socket.io/?EIO=3&transport=polling&t=MdZoLnn
net::ERR_SSL_PROTOCOL_ERROR
Where as if I watch for the Server ip like this:
const socket = io('123.123.123.123:3333', { secure: true });
I get this error:
https://123.123.123.123:3333/socket.io/?EIO=3&transport=polling&t=MdZpRnE
net::ERR_CONNECTION_TIMED_OUT
The site has an let's encrypt ssl certificate, further the webserver is nginx and the os is ubuntu. On my local window (wamp) it works starting it with node socket.js.