For some reason you need the router to have a very different IP address than it comes with - 192.168.1.1. Let's say your network is going to work in the 172.16.100.X address space, so you'll need to change the whole address of the router. In order to do this, you will probably have to adjust the computer's network settings to work with the default address-this is usually best done by manually setting the computer's IP to something like 192.168.1.11. Changing the router's address is no problem; you connect to the router with your browser using its current IP, change the numbers in the little windows, and click "Apply." The router makes the change and probably reboots itself.
Unfortunately now you can't access the router. That's because your computer still has an address in the 192.168.1.X address space (and probably a net mask of 255.255.255.0, which limits you to only those addresses that match the first three octets).
Now to to access the router you'll have to change a few of your computer's network settings. Here's how. How you proceed depends on how your computer's address is set. If you manually set the computer's address to 192.168.1.x, you'll need to change that address to one in your new address space. If you had a static address of 192.168.1.11, in this example you'll need to manually change it to 172.16.100.X (any number between .1 and .253 that isn't already taken will work). If you didn't manually set the address, and the computer's set to automatically obtain an address, you just tell the computer to release its current address and get a new one.
In Windows operating systems, open a command prompt and type "ipconfig /release," which dumps the automatic address it had, and then "ipconfig /renew," which gets a new address, which will be in the address space that you just changed the router to. Of course you won't type the quotes, and depending on which Windows version you have you may need to make it "release all" and "renew all."
For Mac OS, either restart your computer, or go to the Apple menu, choose System Preferences, choose Network from the View menu, and then Active Network Ports from the View menu. Deselect the "ON" checkbox for your network adapter, click on Apply, then reselect the "ON" checkbox and click Apply again.
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