Error Loading Rss

Hi everybody,
i try to load RSS feed from a docker hosted rss mixer.
At the moment i only see: Error loading RSS Feed
If i´m in the docker container and wget to my address i get the information i need.
in chrome console i only see mixed content or cors erros.
someone here to help me?
thanks
kind regards

this sounds like the CORS issue, which is known:

and what can i do to prevent this?