NUKI 3 Pro connection delays from phone

I have NUKI 3 Pro with enabled Wi-Fi and Bluetooth.
When I go home and come close to my door , I press in phone app. “unlock” and I see my phone is exactly switching cellular internet to home router and the wi-fi signal is pretty weak outside the door.
It takes 10-40 seconds to NUKI to get command to open.
If I disable wifi in my phone (for experiment) and stay with cellular internet . I get quick response. Also if I at home connected to wifi I get quick response.

So , why NUKI and phone don’t try to connect by Bluetooth ?

This is not cool to stand behind the door for so much time and wait for something to happen.

It does, but if there is internet connectivity available it tries to connect first via that and falls back to BLE only if internet does not work which takes some seconds (up to ~10s).

Btw. Auto-Unlock always uses BLE.