I can connect to Wi-Fi when I use RPi 3B but when I boot the system with 3B+ it doesn't connect to Wi-Fi automatically and when I click on the top right to connect it to Wi-Fi, I see the error:
no wireless interfaces found.
We tried
sudo rpi-update
sudo apt-get update
sudo apt-get upgrade
and some other common solutions on the internet but none of them solved the problem. I can connect to internet via Ethernet but I need to connect to Wi-Fi. I also tried to set the country code but it did not work.
Are there any other solutions we can try?
sudo apt-get update; sudo apt-get install --reinstall raspberrypi-bootloader raspberrypi-kernel
will put it back to the latest supported kernel/bootcode. THEN you can start solving your problem.