Access Home Assistant Behind a firewall without specifying port number

Hi, great people.
I need help. I have been battling with this for sometime.

I have an HA that works well and I can reach it via the internet with properly forwarded ports. I even set up duckdns so that I can reach it via hostname.duckdns.org:port number.

What I want to do is to be able to reach it via hostname.duckdns.org. Is that possible. Apparently my local ISP can only assign private IP which is why I needed to forward the ports to the open ports the ISP assigned to me. I have tried duckdns and nginx add-ons without success, I always have to append the ports.

Any help is appreciated. Thanks.

I used to have the same issue when I was using port forwarding, forgot what I did to fix it back then.

Is the port forwarding from 443 (external) to 8123 (internal) ?

Take a look at Zerotier. No firewall/port forwarding required.