Daniele_Sunrise Thanks for your support! This didn’t work either.
For the record, I did not reset my router to factory settings as suggested by manual, but there is possibility to start the wizard manually. I would strongly like to avoid restarting it to factory settings as I have many other custom configurations for my local network.
The router was used with UPC / Sunrise, as I described in my initial post. It was connected to old Connect Box (white) for cable internet. Connect Box was in bridge mode (modem). In this case my router got public IP automatically.
The only way it works now is if router is connected to Connect Box 3, from which it gets local IP address.
Here is the screenshot of current WAN settings page
