The DD-WRT poison pill

At work, we’ve been using Linksys WRT54GL wireless routers running the DD-WRT (v23sp2) firmware for quite some time now.  Not only can you usually get these routers for $49 at, but they can be loaded up with tons of different 3rd party firmwares – many of which include bumping up the transmit power of the device.  Also, they have removable antennas (antennae?) that can be helpful when you are trying to get your wireless signal further, more directional, a larger spread, or what have you.  Now I recommend the WRT54GL + DD-WRT combo everywhere that I’m asked to help with a wireless setup.  It’s nice to have some consistency!

Anyhow, something has been amiss since I introduced an additional wireless access point in our new suite here at work.  Basically, I was setting up a third wireless unit using the same ssid, but a different channel.  (This allows for fairly seamless wireless “hopping” around the office without having to join every client up to different wireless networks.  Make sense?  Join once, browse all over the place.)  Since adding the new wireless access point, however, folks have been complaining about “being able to join, but then they can’t browse”.  Wacky.  It seems as if people are joining access points that are further away, which results in a very poor signal and interrupted (if not totally unavailable) network access.  Ugh.

In what is generally considered a poor troubleshooting tactic, I decided to upgrade to the new DD-WRT v24sp1 firmware as a “fix”.  Perhaps there is something in the new firmware that handles this type of setup better?  I upgraded two of our three access points, and the update performed flawlessly.

Or so it seemed. 

After the update, I connected to the web interface of both devices, and all seemed well.  The previous configuration ‘persisted’ through the upgrade, which was nice.  Then things got wonky.  Pretty soon I couldn’t connect to either of the upgraded devices, my third (un-upgraded) device was no longer accessible, and folks were reporting strange goings-on with our network – particularly the wireless.  I restarted both of the “upgraded” access points, but no luck.  Finally, I took them both off-line entirely and things got better – minus wireless connectivity, of course.

I had a sneaking suspicion that my upgraded devices had “reset to defaults” somehow.  It was just a hunch.  I grabbed a laptop, connected directly to one of the upgraded access points, and hit the default IP address of in the browser.  There it is!  The DD-WRT status screen was prompting me to change my username and password.  It had, in fact, reset to the defaults, which means that it’s trying to hand out IP addresses in the 192.168.1.x range on our 10.1.1.x network.  Having two rogue DHCP servers handing out bad addresses is a poison pill in your network.  Not good.  Trust me.

Anyhoo…both access points were easy enough to fix, but it’s still odd that they reset themselves after a successful upgrade where I was able to verify that their previous settings had carried over.  Very odd indeed.  As a test, I upgraded the third access point as well.  Same results.  It upgrades successfully, appears to be fine, and then tanks – resetting itself to defaults.

All that said, I still stand behind DD-WRT as a reliable firmware option for the WRT54GL devices – but watch what you’re doing, and “reset to defaults” with each upgrade.  If not, I guess it’ll do it for you!  Also, I’ve found that spreading my access points across further channel frequencies is a good thing.  We’re currently running on channels 1, 6, and 11.  Seems to be working well, and was perhaps the entire issue all along….


4 Responses to “The DD-WRT poison pill”

  1. 1 Matt Swann November 10, 2008 at 6:59 pm

    If I remember correctly, each wireless channel spills over a bit into its neighbors’ bandwidth… so a device on channel 2 will cause some interference on channels 1 and 3.

    The reset-to-default behavior is wacky. Does this mean that, after a new DD-WRT release, I should drive around looking for access points that have been reset and thus have predictable admin passwords?

  2. 2 yipcanjo November 10, 2008 at 7:04 pm

    You’re right about the spill-over behavior, though I think it reaches even a bit further — like Channel 3 would carry over to channels 1,2 and 4,5. I think.

    I don’t understand the reset issue, but you can certainly drive around and look for those! It resets them to — get this — SSID: dd-wrt, default user/password, and no wireless security! Yikes 😦

  3. 3 kdogg1 November 10, 2008 at 11:02 pm

    Funny enough, I had this very same thing happen on my very same router. Though I was not using a 3rd party Firmware version. Turns out I had a hit to my power and that scrambled the brains so to say of my router. I had to go through and reset the whole thing…Pain in the butt to say the least!

  4. 4 yipcanjo November 10, 2008 at 11:17 pm

    Power blips can definitely reset your router to “defaults”, which is pretty obnoxious. I always recommend taking a “backup” of your router config after you’ve set it up, and then every few months afterward. Could save a LOT of headache down the road! 🙂

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