Nginx 负载均衡 upstream不精准

server
{
    listen 443 ssl http2;
    server_name xxx.cn;
    #SSL-START SSL相关配置，请勿删除或修改下一行带注释的404规则
    #error_page 404/404.html;
    ssl_certificate    /www/server/panel/vhost/cert/xxx.cn/fullchain.pem;
    ssl_certificate_key    /www/server/panel/vhost/cert/xxx.cn/privkey.pem;
    ssl_protocols TLSv1.1 TLSv1.2 TLSv1.3;
    ssl_ciphers ECDHE-RSA-AES128-GCM-SHA256:HIGH:!aNULL:!MD5:!RC4:!DHE;
    ssl_prefer_server_ciphers on;
    ssl_session_cache shared:SSL:10m;
    ssl_session_timeout 10m;
    error_page 497  https://$host$request_uri;
    #SSL-END

    location / {
        proxy_http_version 1.1;
        proxy_set_header Connection "keep-alive";
        proxy_set_header X-Real-IP $remote_addr;
        proxy_pass http://callback.com;
        index index.php;
    }

    location ~ .*\.(js|css)?$
    {
        expires      12h;
        error_log off;
        access_log /dev/null; 
    }
    access_log  /dev/null;
    error_log  /www/wwwlogs/zhengnengliang01.cn.error.log;
}Copy

  upstream callback.com{
   server a.x.x.x:9001 weight=1;
   server b.x.x.:9001 weight=2;
   ...
   ...
} Copy

server
{
    listen 9001;
    server_name a.x.x.x;
    index index.php index.html index.htm default.php default.htm default.html;
    root /www/wwwroot/VideoApp/public;
    include enable-php-74.conf;
    include /www/server/panel/vhost/rewrite/a.x.x.x.conf;
    location / {  
        try_files $uri $uri/ /index.php$is_args$query_string;
      }Copy