Unable to connect macbook air with wifi.

I am having trouble to connect my mac book air 13 inch early 2016 edition to any wifi network. I have tried all the possible troubleshooting steps from DNS server to safe boot and recovery. I also had an hour long discussion with an apple care customer support, and performed every step as he guided but still the issue is unresolved. The only way I can connect to an internet network is through ethernet cable or when I connect my iphone via usb, I am able to access the internet.

any suggestions or help would be appreciated!

thanks