Hmmm. I can connect using HTTP but that redirects me to HTTPS which then times out.
Do you have port 443 configured and open? Is this a residential setup? Have you setup the required NAT or port forwarding like you did for port 80?
curl -I http://n00bserver.duckdns.org/
HTTP/1.1 301 Moved Permanently
Server: nginx/1.26.2
Location: https://n00bserver.duckdns.org/
curl -I -m7 https://n00bserver.duckdns.org/
curl: (7) Failed to connect to n00bserver.duckdns.org port 443 after 91 ms:
No route to host