The Linksys WRT54GL is arguably one of the most rock solid home/office routers that one can buy today. Even though the hardware is becoming more and more dated running one with a custom firmware can give someone like me (a nerdy hobbyist) an extremely powerful router for a relatively low price.
I recently traded my dad my never WRT110N wireless-N router for his older WRT54GL purely for the ability to run custom firmware. Unfortunately I also learned something pretty interesting about how these routers behave.
On my way back from home where I picked up the 54GL, I was also transporting a set of computer speakers. Consequently, the two devices have remarkably similar power supplies. Here's the main difference: the Linksys adapter outputs 12V DC and the CyberAcoustics adapter outputs 9V AC. Other than that the two adapters look identical from a quick glance and here's the kicker, they have the exact same plug on the other end. If they were obviously different sized then I could have avoided a few hours of headache.
Now as the story goes, I of course grabbed the wrong one and fired up my "new" router. I will say that I had already tested it before I left and it was in perfect working order. Somehow between there and here the device broke. With the other power supply the lights still flashed and everything seemed to work, except for the fact that the little blue and black box had a constantly flashing power LED was resetting itself every 20 seconds.
After reading numerous posts and trying different things, someone finally mentioned that using the wrong power supply can cause strange behavior in these Linksys routers. (Of course at this time, I had not realized my error and brushed off the suggestion). I had reflashed the stock firmware, nothing... Nothing was working.
It was about 2 hours while unpacking the rest of my stuff that I noticed the shiny Linksys sticker on a power supply in my bag and knew that had to be the cause of my problem.
Well after plugging in the correct power supply and trying again the router stopped rebooting but was essentially dead to the outside world. It appeared that using the wrong power supply corrupted the firmware of my device! As a last resort when the stock firmware would not boot the device I tried a long shot and used TFTP to flash the "recommended" build of DD-WRT to it. On the PC console there was a success message, but the router still didn't spring back to life. I noticed one more piece of important instruction: please wait at least 2 minutes after flashing for the router to load the new firmware. Sure enough, after all that headache I was finally up and running again. Ughh. That was fun =]
The instructions I followed can be found here: