Weird problem with wireless modem / router - connection dies after 20 minutes.

June 18, 2007 3:44 AM

Weird problem with wireless modem / router - connection dies after 20 minutes.

This is one issue that has failed me, the technical support guys, and Google. Coming in here as one of the last resorts :-)

I am using an Aztech DSL600EW wireless modem / router. It is hooked up directly to a desktop at home. I connect to it wirelessly on my laptop which I use at work and at home.

The problem is weird - after connecting for about 21-23 minutes (never more, never less) - the wireless connection on my laptop would fail. I cannot load up any websites - the connection is as good as dead. I'd also end up losing my local IP address.

Meanwhile, on the desktop computer connected via a normal network cable - everything's normal. The Internet connection is perfect. The only thing is that after the same 21-23 minutes, it would not be able to open up the router's web-based control panel (usually accessible via 192.168.1.1).


The only way to regain normal functionality is to reboot the router. Now imagine doing that every 20 minutes!!! Needless to say, my annoyance level is sky-high, even more so when there are no solutions to be found.


I've tried re-setting the router, looked up every configuration option, and even had the unit exchanged twice at the Aztech branch office - and the technical guy there didn't know what to make of it.


I don't think it's a problem with my laptop - I use another wireless connection in the office and that's fine.


So... someone HELP! Please...

posted by arrowhead to Computers & Internet (3 answers total)

I don't know the router involved, but this sure sounds like an issue between the router and your laptop re-negotiating wireless encryption keys, if you have WEP or WPA enabled. Some router software has a configurable interval for the re-calculation and exchange of new encryption keys between clients, while other routers (perhaps in the interests of simplified set up) just use a default value loaded from firmware. The router works for 21 minutes, because it first uses a pre-shared key value you set in it, and in your laptop. What fails are subsequent automatic negotiations and exchanges between the router and laptop, where this initial pre-shared key is discarded in favor of a newly computed key pair usually based on pseudo-random numbers that the two devices agree to use. The idea behind this is that by re-computing and exchanging new key pairs at fairly short intervals, you keep people sniffing packets from having enough time to break the encryption by brute force attacks.

As to what you can do about it, first thing to check is that your router is running the latest firmware available for it. Next might be to consider replacing the factory firmware with an open source alternative such as OpenWRT. Fortunately, it looks like your router is a supported device for OpenWRT. That may give you a finer degree of control over security settings, and resolve your problems.
posted by paulsc at 5:08 AM on June 18, 2007

I have a similar issue at home on my Windows machine, but mine is (Seemingly) not a WEP key issue. After looking at all of my variables, I have determined my problem to specifically arise when the machine goes into hibernation. I always lose connection when the machine goes to sleep, and it seems to be a DNS issue. Rebooting solves the problem, but so does re-starting my software firewall (ZoneAlarm).
posted by dontrockwobble at 6:00 AM on June 18, 2007

I had the exact same problem at my office.

It's *not* a WEP issue. I know this because I spent pretty much all day Wednesday, Thursday, and Friday of last week alternating time on the phone between LinkSys and SBC/Yahoo!/AT&T. (LinkSys was no help at all, btw.)

Here are the two best things to try to fix it:

1. Make sure there are no printers on your network with hard-coded IP addresses attempting to connect to a DHCP server. I have no idea why this may be a problem, but when I disconnected the printers the problem disappeared.

2. [Not likely going to help, but ...] Another thing the DSL rep(s) told me to do was to disable NAT *and* DHCP on my DSL router and hard-code a single IP address to the wireless router (because the wireless router is going to be doing the assignment of internal IP addresses and because unless you're connecting something other than the wireless router to the DSL modem, it doesn't need to worry about handing out IP addresses).

Disclaimer: IANANA (I am not a network administrator.)
posted by GatorDavid at 6:34 AM on June 18, 2007