Port not accsessible outside of home

I cant get port forwarding to work i set everything up. i already restarted the router.
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i know its better to use duckdns and i will once i got the basic configuration going.
but i cannot reach it
On canyouseeme.org it says the following:
Error: I could not see your service on 87.169.. on port (8123)
i dont know what i did wrong. do i have to set up anything with the homeassistant itself.
When im at home i can easily access with http://homeassistant:8123
what am i doing wrong?

Thanks for answers