Binding a DNS to my application server

Hello!
I have a DDNS (provided by no-ip) and its already pointing at the machine that my application server is running, whit let’s encrypt I got a cert and key, and they are set fine, but when I try to connect to my application server (bind in port 8080) i got this error on the TLS: SSL_ERROR_BAD_CERT_DOMAIN
The DDNS is pointing to the port 8080
The problem seems to be that the hostname in the certified is something like “example.ddns.net” but when I access to the site from “example.ddns.net” (showing that the bind between the DDNS and the ip and port is right ) it change back to the ip, so It tries to verify the certificate whit the IP not whit the DDNS.
any advice?

For anyone asking, I solve the problem, I will document my entire process here in hope that it may be helpful for someone.
In no-ip webpage I configured the DDNS as a DNS Hostname (A), then I use certbot to get a certificate from that DDNS, after that I just set the key and certificate in the application server configuration file, at that was all.
The I just to go to my application server it was just:
https://example.com:8080
I hope this may be helpful to someone