Ubuntu 即使呼叫来自同一服务器，socket.io也会通过CORS策略阻止我

我越来越

访问位于的XMLHttpRequest 'https://example.com:3003/socket.io/?EIO=3&transport=polling&t=NFm_Nq4' 源于https://example.com'已被CORS策略阻止：否 “Access Control Allow Origin”标头出现在请求的服务器上 资源

myserver.js

var app = require('express')(); 
var io = require('socket.io')(server);
var debug = require('debug')('Gentack:Chat');
var request = require('request');
var dotenv = require('dotenv').config();
var socket_url = process.env.APP_URL;

var port = process.env.PORT || '3003';

if(SSL_KEY && SSL_CERTIFICATE) {

    var fs = require('fs');

    var https = require('https');
    
    var server = https.createServer({     
                    key: fs.readFileSync("/etc/letsencrypt/live/example.com/privkey.pem"),
                    cert: fs.readFileSync("/etc/letsencrypt/live/example.com/fullchain.pem") 
                 },app);

     
    server.listen(port);

} else {

    var server = require('http').Server(app);

    server.listen(port);

}

我检查了3003端口，它是打开的