I've just bought a second-hand Linksys WRT54GS (v4) with intention to put DD-WRT on it. Unfortunately, I have problem with software currently running on this device.
It has Sputnik based on firmware version 4.70.6. This version number seems like from v3 hardware version of this router. I think that before Linksys made firmware specific to the v4, the same binary was used for v4 and v3.
The problem with that old Sputnik is that I can't reflash it with another firmware. I've tried with latest Sputnik, initial DD-WRT flash (from Sputnik website) and clean Linksys firmware for v4. None of that works, flashing process just stops with error (I'm using web-based interface for flashing and done 30-30-30 reset before attempts).
Then, deep in the internet I found something that seems like a solution - somebody successfully downgraded from Sputnik v4.70.6 to clean v4.70.6 and then to v4 firmware. So why I'm writing this instead of downgrading my router software? Because it seems impossible to get that crucial Linksys firmware for WRT54GS hw v3, v4.70.6. It has been taken down from Linksys website and all links I have found are dead. The support guys claim that they don't have that file (that means "we are not authorized to give it to you" for me).
So, if some of you has this file left on hard drive, I would be very glad for sharing it. Or, if you have some other ideas on how to put DD-WRT on it, that would be also very welcome.