wifi network not visible on my Macbook Air. I can connect same network over my iPhone

I have a new wifi router and my Macbook Air connected to it smoothly for the first week. Now the wifi is just not visible on the laptop. I continue to connect fine with my iPhone, iPad and Lenovo Thinkpad, so its definitely not an issue with the router.

I also tried to manually identify the network and connect to it, but that does not work as well.

Has anyone faced this earlier and knows the fix?

Thanks,

Rahul.