Wifi do not connect
When MAC book is looking for wifi network all the time and do not connect.
The best 100% solution is to remove the wifi component from Network preference and others like blue tooth etc.
Then add wifi only and it will work.
Only renewing and re-joining wifi will not work. You need to remove Wifi icon from the left pane of network preference and it will 100% work. The reason is Wifi sticks to old network and cache makes it worse so you need to clear the cache.