(2) Cisco E3000 routers "bouncing" wireless connec

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DD-WRT Novice

Joined: 27 Jan 2012
Posts: 14

PostPosted: Fri Jul 06, 2012 2:12    Post subject: (2) Cisco E3000 routers "bouncing" wireless connec Reply with quote
I searched and haven't found anyone having the same problem.

I read all the "read this first" stuff and am trying to follow what I believe to be the protocols - please forgive me if I've missed something!

I'm an IT consultant by trade, and always err on the side of "too much info" rather than "too little"... So PLEASE bear with me here too!

I have two Cisco E3000s (Broadcom BCM4716 chip rev 1)

I set them up ...

(DD-WRT v24-sp2 (12/24/10) std-usb-nas-build 15962) -

here's the thread I created at the time:
http://www.dd-wrt.com/phpBB2/viewtopic.php?t=150496 -

...around Feb. 1 and they've been working BEAUTIFULLY until the last couple of weeks.

They started dropping wireless connections. The connection will drop for ~15-20 seconds, then reconnect for 15-20, then drop, then reconnect...

This affects all client devices, apparently at the same time.

The clients range from an old Dell D600 LT to a brand new quad-core Asus, an iPad2, iPods, Zunes, new LG TV, Sony BRD, Pioneer Audio receiver...

It seems clear that the router is intermittently shutting down its wireless radio - all connections on all devices seem to drop at the same instant.

Whenever one router does this, the other will do the same within minutes to an hour or so.

Physically unplugging the power, waiting ~10+ seconds and reconnecting seems to be the only thing that will make them stop, but they'll do it again in minutes, hours or days.

#1 - "Gateway" - is located downstairs in my "comm closet." It's hanging vertically - RJ45 ports down - about 6" off the wall so as to allow airflow to all sides.

All DHcP/DNS/Etc functions are disabled - I'm still running those on my old router as I just never got around to moving them to the new ones. It seems the 'WAN' port on my old one died, which forced me to replace/upgrade, but since the cpu and all still worked fine I've left it in place to handle all the "server" functions.

"Gateway" is connected to my cable modem via its WAN port.

#2 - "Upstairs" - is where most clients usually connect. It's upside-down on top of a "computer desk" hutch in my bedroom.

Its WAN port is disabled, it's connected via one of its LAN ports to a LAN port on "Gateway".

I'm aware of the heat-problems with these routers - hence the odd placement. When this started, I put a small fan blowing directly on each of them, but this doesn't seem to make any difference.

The comm-closet gets warm when the doors are closed, but oddly the upstairs is the one that usually starts acting up first. The temp in the upstairs bedroom never goes above 75 or so.

The routers originally shared the same SSID ("ciscoWLAN") but when this started, as part of my troubleshooting, I changed "Upstairs" to use a different SSID ("ciscoWLAN2") - this made no apparent difference so I put it back to original SSID ("ciscoWLAN")

I originally intended to use the USB functions to attach a HDD for file-services, but have been running those off my boxee-box so those services remain disabled on both routers.

The load numbers are always low - usually under 2-3% - and I've never seen memory use above 25% - I'm not straining these things at all!

Other than the aforegoing, I don't know what other info may be useful, but if you'll ask I'll be happy to obtain anything you need!

I'd appreciate any input you may have. If you need more info please let me know and I'll gladly provide it!

Thanks in advance for your time!

Joined: 13 Jul 2008
Posts: 51
Location: MI, USA

PostPosted: Fri Jul 06, 2012 2:53    Post subject: Reply with quote
Check your TX power, it may be too high. Also make sure the channels your using are the least crowded.

Additionally please read the entire E3000 wiki article
DD-WRT Novice

Joined: 27 Jan 2012
Posts: 14

PostPosted: Fri Jul 06, 2012 3:03    Post subject: Reply with quote
Thanks for your time!

1) I made no changes to any power settings, they're currently at 71 mw

2) Will read again - likely tomorrow, doubt I could follow it ATM - thanks for the link!

ETA: I'm confused by this bit:
You can use some of these figures to come up with what Tx power rating would be best for you. As factory lists it a max of 20dBm then a setting of 100mW could be used as 20dBm = 100mW 17dBm = 50mW and so on.

How does one convert dBm to mW?
Is my default of "71mW" not OK?

3) I live in a VERY rural area, can occasionally catch a whiff of a neighbor's sole router but when I've looked they're always on a different channel... Mine are set (defaults) to "Auto", currently both are on ch 3... can't "see" neighbor at all ATM...

Thanks again for your time!

Joined: 13 Jul 2008
Posts: 51
Location: MI, USA

PostPosted: Fri Jul 06, 2012 3:58    Post subject: Reply with quote
71mw is a bit high for my taste. I would try 30-50mw. You may loose signal strength and link speed but you should gain stability assuming the routers are not too far apart.

Joined: 22 Sep 2008
Posts: 11196

PostPosted: Fri Jul 06, 2012 4:54    Post subject: Reply with quote
I have that router running that build and it is rock solid for me on 2.4 ghz. I suggest doing a hard reset and reconfigure from scratch. Check for wireless interference too. I use default tx power. Not sure that changing it does anything on that router...
I'm trying to teach you to fish, not give you a fish. If you just want a fish, wait for a fisherman who hands them out. I'm more of a fishing instructor. So See this:

LOM: "If you show that you have not bothered to read the forum announcements or to follow the advices in them then the level of help available for you will drop substantially, also known as Murrkf's law.."

Joined: 13 Jul 2008
Posts: 51
Location: MI, USA

PostPosted: Fri Jul 06, 2012 6:52    Post subject: Reply with quote
The greater the TX power the more heat the unit will produce. The increased heat can reduce stability. I have a WRT610n v1 and running either radio above 50mw generally results in instability. Its not likely but its also possible the power required to run the radio at 71mw overloads the power supply.
DD-WRT Novice

Joined: 27 Jan 2012
Posts: 14

PostPosted: Mon Jul 09, 2012 1:14    Post subject: Update, little more info... Reply with quote
First, thank you all for the input!

Here's an update:

I first changed the way I had the fans blowing on the units - I wanted to eliminate (if possible) heat from the list of questions...

At this point I believe it's safe to say that heat is not the issue - with the fan literally sitting ON the upside-down router, blowing directly down onto it, they continue to periodically start acting up even though they no longer even feel warm to the touch.

My wireless thermometer says they're running at <80 degrees, so I believe it's safe to say at this point that heat is NOT the issue!

I've been paying close attention and still can find no pattern to when they'll start acting up.

Since my last post I have noticed that when watching the "link status" tab in the "dell wireless WLAN card utility" on my old Dell D600 that the "encryption type" entry will change from "AES" to "AES-(key absent)" then to "TKIP-(key absent)" (just for a second or so each) before it shows the connection as dropped and all the "status" values blank out.

I BELIEVE the connection has actually dropped, and the Pc is trying to re-connect when this happens, but no way to be sure at this point...

Once this happens one time it will continue to "bounce" all devices in the house until I reboot the router...

For clarity, before I go on, the "71mW" TX value was the default - I hadn't changed that or much of anything else - I just did the most basic set of config to get them working, expecting to "tweak" them later once they proved stable...

Next I decided to try "foxale08"'s suggestion and lower the TX value from the default of 71 down to 50mW. I did this and rebooted both routers - now I'm in "wait and see" mode, waiting to see if they'll act up again or if this has solved the problem...

I'll post again as soon as I have something else to pass along...

Thanks again for your time and attention!
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