SSL Setup issues

Using HASSIO .084 with the DuckDNS addon. However, I cannot access HA via https, only http. Below are my settings. Any help in identifying a setup mistake I’ve made would be greatly appreciated.

DuckDNS:

{
“lets_encrypt”: {
“accept_terms”: true,
“certfile”: “fullchain.pem”,
“keyfile”: “privkey.pem”
},
“token”: “redacted”,
“domains”: [
REDACTED.duckdns.org
],
“seconds”: 300
}

configuration.yaml:
http:
base_url: !secret base_url
api_pasword: !secret http_password
ssl_certificate: /ssl/fullchain.pem
ssl_key: /ssl/privkey.pem

secrets.yaml
base_url: https://REDACTED.duckdns.org
http_password: REDACTED

Router:
External Port: 443
Internal Port: 8123

remove the https:// from your base url

Thank you for the reply. When entering the address into the browser (https://REDACTED.duckdns.org), I get the following:

This site can’t provide a secure connection

REDACTED.duckdns.org sent an invalid response.

you removed the https:// and then restarted HA? Are you testing from a connection that is not on your local network?

Correct, I removed https://. Restarted HA. Same issue.