OS X Yosemite: Solve problems connecting to the Internet
If you can’t connect to the Internet, there may be a problem with your cables, your devices, your network settings, or your ISP.
Use Network Diagnostics
You can use Network Diagnostics to solve problems you’re having with a network connection you already have set up, Wi-Fi for example.
Check your Wi-Fi connection
If you’re using a Wi-Fi network, make sure your computer is communicating with the wireless device that is connected to the Internet.
For more information on connecting to the Internet using Wi-Fi, open AirPort Utility, then choose Help > AirPort Utility Help.
Check your cables
Make sure all cables are properly connected. If you’re using an external modem, be sure one cable firmly connects the modem to your computer, and another connects the modem to a working wall jack.
Check external devices
Check that all external devices such as modems, hubs, and routers are plugged in, turned on, and have started up completely. Try resetting these devices by unplugging them for a couple of minutes, then plugging them back in.
Check the indicator lights on the device to see whether the it’s registering a connection to the network and to your computer. If an indicator light does not come on, refer to the documentation that came with your device or contact your ISP.
Check your settings
You can check your settings and the status of each network service, such as Wi-Fi, Ethernet, and Bluetooth in Network preferences.
Choose Apple menu > System Preferences, then click Network.
The network service you are using should have a green indicator and the word “Connected.”
To view more information about your network service, click to highlight it. For additional help, click the “Assist me” button.
Check your Internet service
If all of the above are set up correctly and you still can’t connect to the Internet, call your ISP. There may be a temporary problem with the service.