Router signal and modem signal confirmed, but internet will not work when hooked up through router, just when hooked up to modem. Other computer's internet not working either. Is the problem the firewall?

Modern high-speed internet connections are made using DSL or cable modems. In general, most DSL modems also act as routers, but not too many cable modems act like a router.

Some internet connection basics: Every device connected to the internet has an IP (Internet Protocol) address. The address consists of 4 groups of up to 3 numbers each. They would look like this: 123.111.36.145 (0 is the smallest number and 255 is the largest you will see). When you connect to the internet, you are assigned an IP address by your ISP (Internet Service Provider). When you hook up your computer
to the modem, the signal is passed through the device to your computer and the device's IP address becomes your address. This is not secure, as the "bad guys" could type your IP address into their machine and theoretically see your computer and access all your data.

Connecting with your modem: Modems come with a CD nowadays. Running the setup CD makes connecting quite easy. With a DSL modem, you normally have to provide a username and password to log on. Cable modems generally rely on the cable connection to your house to recognize who you are and when you run the setup CD, you are automatically connected.

The router: The purpose of this device is twofold--one is to take the signal you get from your ISP and send it to a number of computers in your home network. The second purpose is to take the IP address and send it to a different address on each computer. This acts as a "firewall" in that the IP address assigned to your computer is no longer the address of the computer. Those bad guys trying to hack into your system will have a much more difficult time.

Types of routers: There are wired routers capable only of hooking up computers with ethernet cable within a network. There are wireless routers--normally these have 4 wired ports and a set of antennas. These function will in a mixed environment of wired and wireless computers. Most people these days are using wireless routers.

In my next tip, I'll describe how you go about hooking up your new router to an existing internet connection.