Bug 836250

[GreyGeek]

Last August folks started reporting that their wireless connection was slowing down. Those with N modulation (120+Mb/s) were reporting that it dropped to g (15Mb/s) or hung and then timed out. All the while, KNetworkManager is setting dumb, fat and happy in the system tray reporting that the Internet was reporting that the Internet was still connected, as did nm-tool. But, a Konsole ping to Google.com times out, and KMail throws an error that it can't connect to the ISP mail server.

I was having those problem, along with many, many others. I downgraded to the 3.2.0-19 kernel and the wireless problem seemed to improve, but the other problems got worse. That's when I decided to test my RAM and discovered that my 11 day 4GB RAM stick was throwing errors. The day before yesterday I pulled the chip and everything became rock solid again. Yesterday I decided to return to the 3.2.0-20 kernel. Today, when I booted up, I started getting the wireless problems again. I went googeling and discovered this bug:
https://bugs.launchpad.net/ubuntu/+s...ux/+bug/836250

Folks using a variety of distros and kernels have reported the problem. Most of the responses in that thread involve the 3.0.0 kernel. The last posting was on 3-16. Someone using the 3.0.0 kernel and the rtl8188ce wifi (which uses the rtl8192ce driver) reported a "fix" by setting the "power off" on the wifi chip. My chip shows its power is off:

$ iwconfig wlan0
wlan0     IEEE 802.11bgn  ESSID:"GreyGeek"  
          Mode:Managed  Frequency:2.462 GHz  Access Point: D8:5D:4C:B9:F4:BA   
          Bit Rate=150 Mb/s   Tx-Power=20 dBm   
          Retry  long limit:7   RTS thr=2347 B   Fragment thr:off
[B]          Power Management:off[/B]
          Link Quality=70/70  Signal level=-22 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:25   Missed beacon:0

Strangely, if I keep a Konsole open and pinging google.com the chip stays in the 150Mb/s (11n) modulation. The ping will pause, on occasions, but it continues. For 20 minutes of pinging I got an min/avg/max of 51/1136/65 ms. If the rate drops to 15Mb/s the connection soon hangs and the ping times out. I have to reset the connection with KNM. I've been playing with the rlt8192ce params: swenc, ips, swlps and fwlps, but no combination seems to help.

The blame was switched back and forth between KNM and the kernel. Those blaming the kernel switched to wicd and their wireless returned to normal behavior.

For those staying with KNM the usual fix is to disable the 11n modulation, which isn't a nice option to me, it is like switching your V8 engine to V2.

The devs are calling it a "nasty" and hard to diagnose bug.

One person claims an interesting solution, claiming:

[LEFT][COLOR=#48423F][FONT=Droid Sans][B]There is a bug in the Debian Avahi daemon in Ubuntu.[/B] And to resolve this you need to edit the following file /etc/nsswitch.conf as follows.[/FONT][/COLOR][COLOR=#48423F][FONT=Droid Sans]Type the following in the command line[/FONT][/COLOR][COLOR=#48423F][FONT=Droid Sans][B] sudo gedit  /etc/nsswitch.conf[/B][/FONT][/COLOR][COLOR=#48423F][FONT=Droid Sans]This will open the nsswitch.conf file in the text editor. Then simply change the following line[/FONT][/COLOR][COLOR=#48423F][FONT=Droid Sans]hosts:          files mdns4_minimal [NOTFOUND=return] dns mdns4[/FONT][/COLOR][COLOR=#48423F][FONT=Droid Sans]to the below line and save the file.[/FONT][/COLOR][COLOR=#48423F][FONT=Droid Sans]hosts:          files dns[/FONT][/COLOR][COLOR=#48423F][FONT=Droid Sans]That is it. Just reset your internet connection or probably restart your system and your wireless connection should be back on top speed. This worked for me like a charm.
[/FONT][/COLOR][/LEFT]

All it did for me was to set my wireless up at 15Mb/s but unable to connect to web pages or ping, even though KNM was still dumb, fat and happy.

Time will tell.

UPDATE: 8:01 CST
My wireless degraded steadily until even clicking a link brought the connection down, forcing me to close and re-establish the connection with almost every page change. With nothing to lose, I plugged in an eth0 cable so I wouldn't be disconnected when I deleted network-manager and network-manager-pptp, and then installed wicd and all the apps whose name began with "wicd-", and the wicd KDE interface. (I'll probably uninstall the wicd KDE interface because it is poorly designed, the icons are too small and it doesn't show enough information.) A side feature of wicd is the right-mouse option called "connection info", which throws up a small dialog showing the ssid, speed, ip, strength, rx and tx. Using the left upper corner advanced display feature I set it to stay above all other apps, and re-sized it to show its info in the smallest area possible. Now I can watch as the speed toggles between 15Mb/s and 150Mb/s. When it dropped to "15Mb/s" that's the clue that it has stopped communicating with the web. Unfortunately, wcid is experiencing the same problems that the plasma network manager showed. So, wicd didn't fix the problem.

That's really sad, because I ran this box for almost 12 hours yesterday after I compiled the rtl8192ce driver and installed it and never had a single drop out.. I've recompiled it against both the -19 and the -20 kernels, and just recompiled it against the -20 kernel a few minutes ago. But, alas, the constant rate switching (dropping out of 11n down to 11g) continues, but not as often. An advantage of wicd is that when the rate downgrade occurs, wicd shows it by lowering the green bar. When it gets too low it turns orange. When the bar drops to about 10% of the full height it turns red and the connection stops. At least wicd isn't lying to me.

[GreyGeek]

I decided to experiment with my wireless box settings because folks said that when they diabled the 11n feature and dropped back to 11g in their wireless router settings they got their stability back.

I did that and wicd became its normal, rock solid self again, giving me 100% of 54Mb/s.

So, I decided to return to the plasma network manager. It only gives me 80% signal strength (from 3 meters! I have four neighbors who are showing 100%!!!), but it is a stable connection.

[MoonRise]

Truthfully, I've had issues with 11n from day one and not just in Linux. Windows as well. Even at work, I've disabled 11n use all together as it caused more issues with users than it was worth trying to track down what the issue is. It is probably a combination of the 11n specification and the drivers that are available. Just my observation anyway.

[GreyGeek]

Since I installed Precise alpha on Jan 3rd I never had a connection or speed problem with this rtl8188ce chip. My problems started when I upgraded the RAM in this laptop from 4GB to 8GB.

My first bank of RAM was a 4GB DDR3 PC3-10600 1333Mhz. I went to Best Buy. They only had PC3-10660 chips, but the techie there said it would "step down" to 10600. I haven't kept up with hardware for years, so what did I know? I accepted the explanation. I still don't know if that "step down" is right or wrong, but that 4GB stick burned out in 11 days. I ordered a 4GB stick from Amazon with the correct PC3 setting and it has been working fine for three days.

I have upgraded to the 3.2.0-21 kernel and my wifi chip and Internet connection is behaving perfectly. I haven't had a single slow down or hang or drop out since I dropped to 11g at 54Mb/s, which is still 3X faster than my ISP bandwidth allotment.

[SteveRiley]

Can you guys with 11n troubles shift your gear to 5 GHz? There's a lot less interference in these frequency bands than in 2.4 GHz, where you're competing with your neighbors and your microwave oven.

[MoonRise]

That may be it. Yes, I'm still on 2.4 GHz. Hmmmmm. Thanks! Will see what that does.

[GreyGeek]

Not for me. My wireless router is b/g/n only. It doesn't support 11a. The 5 Ghz band is more lonely, but it does lose more energy through walls and obstructions than 2.4GHz signals do. I have 8 partitions between my wireless router and my bedroom (Yes, I surf in bed at my wife's request. :cool: )

[SteveRiley]

(Yes, I surf in bed at my wife's request. :cool: )

Hmm...

* surf in bed as opposed to surf elsewhere
* surf in bed as opposed to something else in bed

...?

[GreyGeek]

I'll never tell!