Websocket connection failed (nginx websocket passthrough)

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

server {
  # your server block here

  location / {
    proxy_pass_request_headers on;

    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header Host $host;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "Upgrade";
    proxy_set_header Accept-Encoding gzip;
  }
}

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

server {
  # your server block here

  location / {
    proxy_pass_request_headers on;

    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header Host $host;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "Upgrade";
    proxy_set_header Accept-Encoding gzip;
  }
}