MET.NO Weatherforecast not working / Help to resolve IP address


I have a strange issue that I would like to share with you. And I need your help to implement a workaround.

I installed Home Assistant (32-bit) on my Raspberry Pi 3+ B yesterday for the very first time. The Installation was running smoothly but the first use case, the weather forecast, doesn’t work.

The home_assistant.log tells me the device has issues to resolve the FQDN:
2020-01-10 13:45:24 ERROR (MainThread) [metno] returned Cannot connect to host ssl:None [Try again]
2020-01-10 13:45:24 ERROR (MainThread) [] Retrying in 16 minutes

I expected this to be a general issue with DNS and spend hours trying to understand the dependencies between the docker image, the host OS, my router and the DNS Service proviced by my Internet provider. Finally I recognized I only have issues with this very URL! I configured a Device Tracker to ping a different service on the Internet and this works perfectly fine.

After another hour I learned my Internet Providers DNS service does not resolve the FQDN. On my desktop PC I added the FQDN and IP address to the local hosts file and now I can connect to the service.

Now my question:
I changed the /etc/hosts file on the host OS on the Raspberry Pi and restarted the DNS service and the Home Assistant but it didn’t help.

What do I have to change to add a static FQDN name resolution?

Kind regards