Set up your router, connect it to the Internet, and connect your PC to the router. Make sure that you connect your PC to it via an Ethernet port, not wirelessly. If you try to upgrade the firmware wirelessly, you could brick your router.

Download the latest edition of the DD-WRT firmware from the DD-WRT site. As I explained previously, check the specific installation instructions for your router, because depending on your specific router model and hardware version, you may need to download slightly different versions of DD-WRT.

In some instances, you'll have to download two versions of DD-WRT -- a "mini" firmware version and then the standard firmware version. In that case, you'd first install the mini firmware, and once that is installed, install the standard version over it.

For the WRT54GL Version 1.1 hardware, download the latest generic firmware version. For other versions of the WRT54GL, such as hardware Versions 1, you'll need to download both the mini and standard. Check the Linksys WRT54G/GL/GS/GX page on the DD-WRT Wiki for details.After you download the firmware and install the firmware, reset your router to its factory defaults. First, log into the administrator screen at 192.168.1.1. Then go to Administration --> Factory Defaults, select Yes, and Save Settings.

Next, do a hard reset of your router by holding down its reset button, which you can find on the back of the router. Hold it down for 30 seconds.Now you're ready to flash the firmware. Before you do it, though, turn off any antivirus software. If antivirus software interrupts the firmware flash for any reason, you could damage your router. And again, remember to do the firmware flash only over a wired connection, not a wireless one.

Log into the administrator screen and select Administration --> Firmware Upgrade. Click the Browse button, and select the firmware you downloaded. The firmware will end with a .bin extension. For my router, I selected the generic version of the firmware, dd-wrt.v23_generic.bin, because that's what is required by this router and hardware version.

Click Upgrade, and then don't do anything. If you do anything at all while the firmware is being upgraded, you could damage your router. It will take several minutes. Next, you should see a screen like the one shown, telling you that the firmware upgrade was successful. Click Continue.You'll be asked to log in again. Your username and password will be reset. The username will be "root," and the password "admin." However, you may not be able to log in yet. Reset your router by holding down its reset button for 30 seconds. You should now be able to log in to your router, and when you do, the new firmware will be there.