Nuki "Incorrect Password for xxx" wifi problem

Hi
With the previous version of Nuki, with the bridge, it worked great. And now on the same wifi network (2.4Ghz) with Nuki Pro 3 (firmware 3.4.10) I have the exact problem.
I tried to create a private wifi network just for Nuki (guests network) but experienced the same behavior-Incorrect password message and unstabelity connection to the network.
When I log into NukiWeb I can see that Nuki connects to the network sometimes, but it is very unstable.