Chances are, part of your home network involves cat5 or cat5e Ethernet cables. If you're using the wrong kind of cable, it could defeat your Internet connection efforts. Crossover cable should only be used to connect two computers directly. If you're connecting devices with a hub or router, straight-through cables should be used. How can you tell the difference? Sometimes crossover cables are labeled by the manufacturer. If not, it's a bit technical to figure out (it involves checking the pairs of wires at the connectors). If possible, just try a different cable to see if that helps.
The problem might be with the computer you're trying to connect to the Internet. Network configuration troubleshooting depends on operating system, connection type and other factors. If your computer has a network icon, it might displays a red X or other error message if there's a problem. If there's no error message and your connection still won't work, some operating systems have the ability to self-diagnose to determine if there's another issue.
If everything else seems to be working OK, then the problem might be with your ISP. Contact its technical support line and ask. If the ISP isn't suffering an outage (they do, from time to time), technical support representatives might walk you through some of the steps you already went though, and they may even be able to test your connection or reset your modem.
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