If my question is off topic then please dismiss me – or if you know where to find the answer please inform me.

In your book “Build Web Servers” 2nd edition you mention the handshake. “The handshake starts with an HTTP
request/response, allowing servers to handle HTTP connections and WebSocket
connections on the same port.”  My question is somewhat related – but is not directly explained to my context – sorry for that. I am aware of your project which includes a SIM-card but that is not suitable for me.

My ESP webserver is running when I am on WiFi. I can press buttons and they respond as they should via Websocket communication. However I would like to reach the webserver from outside via port forwarding. I can open the page from outside, but I cannot execute any command via the websocket. I don’t know how to handle this. When I am home and with WiFi connected  I can open the webserver and execute commands via a Chrome plugin called “Simple Websocket Client”. They respond as they should. But when I am accessing from outside I cannot open the webserver.