400 Bad request

Try using a websocket instead

let webSocket = new WebSocket("wss://807843.xyz");
webSocket.onopen = function() {
  console.log("Connected to websocket!");
};

webSocket.onmessage = function(event) {
  const message = event.data;
  console.log("Received message: " + message);
};

function send(msg) {
  if (webSocket.readyState === WebSocket.OPEN) {
    webSocket.send(msg);
  }
}

/*
# Websocket urls
- cmini: ~/python/cmini
- a200: ~/python/a200
- oxeylyzer: ~/rust/oxeylyzer
- genkey: ~/go/genkey

# How to use
1. open up your browser console
2. paste this code snippet and edit the url
3. call send("your message goes here") 
   to send a message to the websocket
/*