SmartThings could not validate the endpoint configured in 'base_url'

I’ve been migrating Hass.io to a RasPi4 and am having an issue with the SmartThings Integration. I get the error: “SmartThings could not validate the endpoint configured in ‘base_url’. Please review the component requirements”. I don’t know how to resolve this.

I set up DNS and SSL certificate using the DuckDNS and Let’s Encrypt add-on prior to my attempt.

My http configuration is formatted correctly (I am not using port 8123…or 12345):

base_url: https://*********.duckdns.org:12345
ssl_certificate: /ssl/fullchain.pem
ssl_key: /ssl/privkey.pem
server_port: 12345

External access works fine. However, when I input my URL into https://www.digicert.com/help/, I get the error: “Error: *********.duckdns.org is not a fully qualified public domain name or public IP address.”.

Update: Digicert is now giving me good feedback; no issues with my certificate. However, the ST Integration is still giving me the same error.

Im having the same problem. Did you manage to fix it?