First, powercycling your system might do the trick. Here are the steps on how to do that.
1. Shut down all consoles and computers
2. Unplug the router's power cable
3. Unplug the broadband modem's power cable.
4. Wait 30 seconds.
5. Plug in the broadband modem's power cable and wait for its light to appear stable.
6. Plug in the router's power cable once the modem's lights appear stable.
7. Power on the console/computer and test connectivity again.