Register gitlab-runner failing. Bad gateway

I am trying to register a gitlab-runner on windows.

Unfortunately it always results in a “couldn’t execute POST against https://gitlab1/api/v4/runners: Post https://gitlab1/api/v4/runners: Bad Gateway”

In the same powershell console I can happily ‘curl https://gitlab1’ without failure.

I suspect gitlab-runner to always use a proxy, even if disabled in the Internet Options. I can see that when using --debug.
No idea where is retrieves it’s proxy settings from, though. gitlab1 should be accessible without proxy.

Any ideas on how to convince the runner not to use a proxy?

Anything else that might be wrong?

Thaks,
Philipp