[Abandoned] deCONZ

More investigations
Long story short, the Homey Deconz app 1.29.2 lost connection to the pi running deconz.
Wiped the Pi clean, reinstalled everything, still no luck.
I did play around with the REST plugin, the …/config gave me
Port 80
Websocket port 443
Confirmed the Pi’s static address.
So, deCONZ is clearly open on those ports and responsive.
I even found several API keys for the homeyCONZ app in the whitelist section, but none worked trying to manually specify it in the Homey app’s config page, giving me Error when connecting.
If I press request key I get Error: not_found

It seems like something is blocking the app’s connection to the pi.

Please, any ideas?