In our move to improve security in our api landscape, we configured a global redirect rule in IIS to redirect calls to HTTPS.
An unforeseen consequence was that for our (old) WCF services, the WSDL endpoints were no longer accessible. When someone clicks on the WSDL link, a redirect happens but on the https endpoint no metadata is available.
To fix it, I had to update the WCF configuration to explicitly enable the metadata endpoint on HTTPS: