Lights on a Modem / LAN Card.
Generally, there are 04 lights. They indicate the following:
1. Power Light: Shows if the device (Modem)is getting Power Supply or not.
2. Link Light: Indicates if the device is getting broadband/internet signals properly from the ISP
3. Data Light: Indicates wether the internet is working or not.
4. Connectivity Light: Indicates the Modem is connected to a PC or not.