I ran into a peculiar problem at work recently: one of our Linksys WAP54G access points was resetting its SSID and passphrase for no apparent reason.  It’s configured for Wireless Bridge mode, which means that it connects exclusively to another WAP54G in order to bridge two wired networks.  We use this setup to provide network connectivity to a mobile industrial printer on the shop floor.  The printer’s access point was the one that kept acting up, and every time it did it would no longer be able to connect to the AP mounted on the wall.  This was causing a lot of headaches for the people who upload programs to the printer, and for the IT department who had to keep fixing it!  I decided to start researching the issue and see if I couldn’t find a reason for the SSID and passphrase constantly changing on the printer’s AP.

I have to admit that before this problem started, I didn’t know much about the WAP54G as the system had been setup by a consultant.  I found out the glowing Linksys logo on the front panel is also a button, which is used to enter SecureEasySetup mode, or SES.  According to the user guide, pressing it will cause the AP to generate an SSID and WPA-Personal (WPA-PSK) passphrase.  I knew the SSIDs being generated were in the format of linksys_SES_#####, so right away I figured this was the problem.  But why was it happening?

It’s possible that somebody was pushing the button.  I wouldn’t think that anybody would touch the AP, but I’ve worked in IT long enough to know that there are plenty of people who will randomly push buttons and flip switches for no reason whatsoever.  They are the ones who will always push The Big Red Button regardless of any and all warnings not to.  Still, I found it hard to believe that somebody was doing this constantly.  It might explain one or two occurrences, but this was happening at least once a week.  I tried to see if I could disable the button somewhere in the AP’s settings, but it appeared I couldn’t.  I then decided to search the Linksys forums to see if anybody was having similar trouble, and what they were doing about it.

This post by user FredZ caught my attention.  In response to someone else experiencing the same issue, he stated:

The problem you describe has been identified in the past. It seems that some units have have been assembled with the SES switch in the front panel not fully pushed all the way down prior to being soldered into place, resulting in the button being pressed up against the case when assembled, subsequent vibration and/or case movement results in the button being pressed…

You have 2 choices, return the unit under warranty (RMA) or open the unit and seat the SES switch properly yourself (requires some technical ability with a soldering iron).

I thought the unit was old enough that it was probably out of warranty, and I don’t really like dealing with returns and RMAs and all of that anyways.  I decided to open the unit and see what I could do about the SES switch.

I found that the switch seemed a bit stiff, like it might be stuck.  The AP sits on the mobile industrial printer, so it’s subject to being moved, and maybe enough vibration could cause the switch to contact.  I decided to remove the switch.  I’m barely able to solder let alone de-solder anything, but the switch was easily removed with a pair of pliers and a little twisting.  Here’s the board after removing the switch:

You can see where the switch was located on the left side of the photo.  The result?  We’ve gone nearly two weeks now without any problems.  I’m fairly confident at this point that the switch was the cause of the problem.  The forum post indicated that it might be a deficiency in the construction of the WAP54G.  In our case however, I think the industrial environment our unit is subjected to may be a contributing factor.  The constant vibration and dusty air may have led to the switch’s failure.  It had worked for a long time without any problems before.

Given that though, I think Linksys really should have provided a setting that would allow the disabling of the SecureEasySetup switch on the front panel.  I still can’t rule out that somebody may have been pushing the button, and the only way to prevent it from happening without voiding the warranty is to lock the AP up so it can’t be accessed.  Maybe it’s something they could add in a future firmware update, but until then at least I know there is a way to do away with it.

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