Integration with smartthings giving error when open external website

Hello.

When im trying to setup smartthings integrations and i put in the token for smartthings, and press OPEN WEBISTE in home assistant, it opens a new browser and says:
image

If i use my nabu casa base_url it works perfectly, but i have a duckdns.org i setup which i am able to reach from the outside of my network, so all ports and that is setup and working.

I have tried to use the removal tool for HASS, which removed the token as it should.
But so far i cant make the integration work with duckdns activated.

if i look at binary_sensor.remote_ui it also says that its unavailable, but i dont no idea if that is supposed to work without nabu casa.

my configuration.yaml base url config is this:

http:

base_url: https://xxxxxxx.duckdns.org:8123

ssl_certificate: /ssl/fullchain.pem

ssl_key: /ssl/privkey.pem

homeassistant:

name: Home

unit_system: metric

external_url: “https://xxxxxxx.duckdns.org

internal_url: “https://x.x.x.x:8123

if i change the base url to the nabu casa link, the smartthings integration works without a problem, but i wanted duckdns to work instead.

Any suggestions to what i may have done wrong?

SSL-checker also says my url is good, and i can access it from anywhere.