Unable to connect esp8266 via https to socket.io; error 400

[KrzysztofMoskalik]

Hi,

I'm trying connect NodeMCU v3 (esp8266) to socket.io server via https. I'm using Arduino IDE (latest version) and latest version of this lib. Using code from example WebSocketClientSocketIO i cannot connect to server.

Socket.io server i'm using is nodeJs socket.io-server (2.3.1) which is running behind nginx proxy and this proxy is throwing me http error 400. I'm confused, because simple nodeJs client is working for this server:

const io = require("socket.io-client");

const socket = io('https://my-example-host.com', { transports: ["websocket"] });

I've tried both socketIO.begin(socketHost, 443, "/socket.io/?EIO=3&transport=websocket"); and socketIO.beginSSL(socketHost, 443, "/socket.io/?EIO=3&transport=websocket");

also for socketHost i've tried my-example-host.com and https://my-example-host.com.

[KrzysztofMoskalik]

After upgrading to V4 both server and "/socket.io/?EIO=4" all started work properly.

[hoangmanhh99]

@KrzysztofMoskalik can I see your code? I have same issue but can not resolve