How to set up Nginx-Tornado-Websocket binding?

Question

Nginx

Help setting up Nginx-Tornado-Websocket.
Through Nginx, it turns out to load only statics, there is no switching to Websocket.
Standalone (without Nginx) the Tornado application works fine on port 9001 with these settings. Handlers:
define("port", default=9001)

handlers = [
  (r"/", MainHandler),
  (r"/botsocket", BotSocketHandler),
]

Switching to Websocket (js): Nginx settings (all commented out directives are my vain attempts to find a working configuration):
var url = "ws://IP_сервера/botsocket";

worker_processes 2;

#user                    root;
user                    nginx;

events {
    worker_connections  1024;
}

http {
    include             /etc/nginx/mime.types;
    default_type        application/octet-stream;
  
    upstream websocket {
        server IP_сервера:9001;
        #server 127.0.0.1:9001;  
    }

    map $http_upgrade $connection_upgrade {
        default upgrade;
        ''      close;
    }

    keepalive_timeout 86400;
    proxy_connect_timeout 86400;
    proxy_send_timeout 86400;
    proxy_read_timeout 86400;

    server {
        listen 80;

        location ^~ /static/ {
            root /var/www/python/test/;
            if ($query_string) {
                expires max;
            }
        }

         # WebSocket.
        location /botsocket {
            proxy_http_version 1.1;
            #proxy_set_header Connection "upgrade";
            proxy_set_header Connection $connection_upgrade;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_pass http://websocket;
            #proxy_pass http://websocket/botsocket;
            #proxy_pass http://IP_сервера:9001/botsocket;
            #proxy_pass http://127.0.0.1:9001/botsocket;
        }

         location / {
            proxy_pass_header Server;
            proxy_set_header Host $http_host;
            proxy_redirect off;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Scheme $scheme;
            proxy_pass http://127.0.0.1:9001/;
        }
    }
}

In the current Nginx configuration, in response to a request to switch to Websocket, I get a 403 error.
Changing the user in the Nginx configuration from nginx to root also doesn't change anything.
Help with advice, for the second day I have been fruitlessly digging in Google on other people's configs, which do not work for me.