Problem with WiFi on Latte Panda 3 delta

Hi there!

I'm trying to set up a Gentoo Linux on the Latte Panda 3 delta - and I am faced with problems with the WiFi card.
The card is detected and it works with my phone's AP - in that case, the connection is stable and all seems to be good.
When I'm trying to connect to my router's AP - nothing happens, the card isn't connecting to the router. I see nothing in the wpa_supplicant logs, so it seems like the problem lies somewhere deeper. BTW, the router's AP is seen in WiFi scans - so the WiFi card can see the AP, but can't connect.
 

An interesting moment is - with Ubuntu, the same Latte Panda 3 delta board IS connecting to the same router and the connection seems to be good - so it seems to be a software issue for sure. 
I had a theory that this may be firmware for the WiFi card, so I took firmware files from Ubuntu and tried exactly the same firmware with Gentoo - but with no luck…

So, is there a known-good kernel .config file for a Latte Panda delta 3? Is there a known-good system configuration (firmware version, wpa_supplicant version, something else) for a LattePanda 3 delta? Is there a reference Linux configuration for this board?

Thanks in advance!