Why does the 400 error occur in the nginx+socket.io+ssl bundle?

Question

Nginx

Good afternoon. For 2 days I want to solve the problem of WebSocket connection to 'wss:// failed: Error during WebSocket handshake: Unexpected response code: 400

location / {
        proxy_pass http://socket_nodes;
                      proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
    }

Help solve the problem

Answer 1

And what do the logs show on what should process the request?