I have a vps hosting with hostinger and I want to add the ssl certificate to secure the website I am using UBUNTU 22.04 and Nginx when I run sudo certbot --standalone -d domain name. I get the error

Hint: The Certificate Authority failed to download the challenge files
from the temporary standalone webserver started by Certbot on port 80.
Ensure that the listed domains point to this machine and that it can
accept inbound connections from the internet.

My website runs on domain-name:3000

server {
    listen 80;
    server_name domain domain;

    location / {
        root fontend/build;
        index index.html;
    }

    location /api {
        proxy_pass http://localhost:8000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
    }
}

Any idea how I could sort that out? I have checked my firewall and it allows traffic on the specified port.