10.10.3 broke my ethernet connection but not my WiFi

Question

I usually connect to the internet on my late 2008 MacBook via Wifi, and when I need the additional speed I just plug in the ethernet cable from the router to the laptop. But following the update to 10.10.3 (and following some changes that needed to be made to the router settings), I can still connect to the WiFi fine, but not with ethernet. Even when I completely remove the router from the equation, connecting to the internet with the ethernet cable directly to the modem does not work. Any help?

Answer 1

1. If the computer is connected through a switch to a cable or DSL modem, and the modem is not acting as a router, then only the first device to connect will get an address. You need to change the configuration of the modem so that it shares its Internet connection with all devices on the local network, or else connect a router.
2. If there are other devices on the same network, and none of them can get an address, then the problem is on the DHCP server (most likely, the router.)
3. If other devices are working normally, or if there are no others, the problem may be caused by a faulty cable or port on the hub. Switch connections with one of the working devices.
4. Open the Network pane in System Preferences and make a note of your settings in the Ethernet service. It may be helpful to take screenshots of the various tabs in the preference pane.
If the preference pane is locked, unlock it by clicking the padlock icon and entering your administrator password.
From the Location menu at the top of the window, select Edit Locations. A sheet will drop down. Click the plus-sign button to create a new location. Give it any name you want. In the new location, set up the Ethernet service with the same settings you used before. Click Apply and test.