Still looking for a solution, I downloaded and installed the “Lamp Finder for MAC” application (https://philipshue.com/lamp-finder-for-mac/), which required me to first install 414Mb of Oracle Java 10. Grmbl! Not really sure why I did this. Getting desperate.
As all three light on the bridge are ON, and only the Hue App seems to be unable to connect ( and yes: both are on the same WiFi network, the bridge has privileged un-routed acces directly into the WiFi, the above check from Steve (https://www.meethue.com/api/nupnp) gives me the correct internal IP address, heck, when I enter the address in a browser, it seemlessly connects me to a page with technical software details, and open source license files/sites. Still – see bottom of photograph : “Connecting …”