I have 20.04 kubuntu. I have my own wifi hotspot from my telephone as my main connection. Hidden and pwd protected.
Every so often my kde wifi connection does not connect and says.. "configuring interface" I try this and then and then reboot and all is fine and connected.
This happened yesterday with another wifi connection also.
I also had the same problem as yours, but with my router's wifi network. It was stuck at "configuring interface".
Somehow, these below commands solved my problem.
Now Reboot your computer and run.