DSL stands for digital subscriber line, and though it has been around as a technology for quite a while, phone companies are just finally starting to utilize it to its fullest abilities. For fast connections to the Internet, the only requirement other than a phone line and a computer is a DSL modem. The DSL modem translates the data over the phone lines and is a simple but critical device. Troubleshooting a problematic DSL modem is usually straightforward.
Make sure all connections in the back of the modem are fully connected and not loose or ripped. If everything appears to be plugged in, try unplugging each connection and reconnecting them back. Restart the computer and see if the DSL modem is providing any connection to the Internet.
Reset the DSL modem. There should be a small pinhole in the back of the modem that you can reset by pushing a pin or the end of a paper lip in and hitting a button. Hold the button in for a few seconds and then release. This should reset the DSL modem and often clears up problems.
Start taking out any unnecessary parts of your network. If you have a separate router remove it from the network and connect your DSL modem directly to your computer to see if you still have problems. This could point to issues elsewhere that are unrelated to the DSL modem.
If everything else is working and you are still having DSL modem problems, contact your provider to see if there is a local outage. Outages, and not equipment problems, are often the reason for a failure to connect to the Internet.