another try for nginx conf

nginx.conf

upstream backend {
    server 127.0.0.1:5000;
}

server {
    listen 80;
    root /ray/ray/yapp;
    index yapp.html;
 
    server_name _;
    
    access_log /var/log/nginx/access.log;
    error_log  /var/log/nginx/error.log;

    location / {
        proxy_http_version 1.1;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-NginX-Proxy true;
        proxy_set_header Host $http_host;
        proxy_set_header Upgrade $http_upgrade;
        proxy_redirect off;
        proxy_pass http://backend;
    }

    location /socket.io/websocket {
        proxy_pass http://backend;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
    }
}