In these situations Wi-Fi has the self-assigned IP address and will not connect to the Internet despite the Internet working on other devices.
On the Network Preferences page the Wi-Fi will also show the Self-Assigned IP Address text instead of connected.
In the main Network Settings window, click on your ETHERNET connection then write down the IP address.
If you are on a private home network your IP should start 192x.x, or in some cases 172x.x.
I tried various suggested methods for fixing this and none of them worked.
However I managed to fix it in the end without any online help, just some common sense and various stages of trial and error.Even if the computer is connected to Wi-Fi network, you won’t be able to use the Internet.To fix Internet not working error due to the self-assigned IP address on Mac, you will have to wipe out some files.You can fix the self-assigned IP address issue and get the Internet to work again on your Mac by simply deleting a few files on your machine. Simply follow the steps below from an administrator account and put the mentioned files in trash. I always go for the Show Networks option as it is easier for me.If you know all your details though, it may be faster to just type them in yourself. If it is a private home network the chances are it will be WPA2 or WEP.Some of the departments have a home run right back to the server; some go through an unmanaged 8 port switch that I installed which then home runs to the server.If I add them to our wifi system - no problems as I can connect wirelessly.I have tried to add a static IP which then claims I am connected but not able to get on the internet.I have spoken to Apple Tech Support who suggested to format the hard drive and install a fresh OS; there are many chats on their community page with suggestions on how to fix this but none of them have worked for me.