NGINX Proxy Manager for SSL and DuckDNS

Hello all,

I am using HA in Docker container along side DuckDNS and NGINX Proxy Manager container.
I am able to access HA using DNS HTTP address from duckdns from internal and external networks. I have added this duckdns URL in NPM and I also see it created an SSL certificate for the URL.
However, when I am accessing the DNS as secure HTTPS. the page is only showing HA logo, “Unable to connect to Home Assistant.” message and it keeps Retrying.
Any clue what I am missing.
I am not sure which details I need to provide but if you please let me know, I will share them.