Challenge failed for domain zepling.com.np

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this is my nginx config file

http{
server {
listen 80;
listen [::]:80;

        location / {
             proxy_pass        http://docker-container-name:8088;
             proxy_set_header  X-Real-IP $remote_addr;
             proxy_set_header  X-Forwarded-For $proxy_add_x_forwarded_for;
             proxy_set_header  Host $http_host;
        }
        location /.well-known/acme-challenge/ {
            root /etc/letsencrypt;
        }
}

}
events {  }