Slow Connection Speed With Intel Corporation Centrino Advanced-N 6235

English Hardware
#1

I have an older laptop that has the Intel Centrino Advanced-N 6235 processor/wifi chip. It is connecting (tested via a speed test page in the browser) at a very slow rate of 4 mbps down, .5 mbps up. When I check all my other devices, they’re connecting at 70-85 mbps down, 20-25 mbps down. So I’m 99% sure the issue is the laptop.

  1. Will a USB-3.0, WiFi adapter fix the issue?
  2. Can I just plug it in and it’ll work in openSUSE LEAP? Or is there some config i need to do?
  3. Is there some other way to fix the wifi than the adapter? Could the OS be throttling?

My setup:
Samsung Series 9 NP900x4C
KDE 5.4.3
Linux: 4.1.15-8-default (64 bit)
Intel i5-3317U
16 GB RAM
openSUSE LEAP 42.1

#2

Check that it is not due to low signal level or interference perhaps. Check the first with

/usr/sbin/iwconfig

Is it possible that you’re connected to a guest wifi account perhaps?

This might show what other wifi signals are around (not a complete test though)

/usr/sbin/iwlist scanning

No, it won’t be the OS throttling in any way. Using another wifi device might help, but that depends on whether or not the current one is the cause of the issue.

BTW, you’re better of testing the network speed using netcat or iperf. A browser-based internet test is not necessarily going to be indicative of LAN performance.

http://deice.daug.net/netcat_speed.html

#3

I get (change identifying info):

wlan0     IEEE 802.11abgn  ESSID:"HIDDEN"  
          Mode:Managed  Frequency:2.412 GHz  Access Point: 60:C4:2C:26:E1:1B   
          Bit Rate=65 Mb/s   Tx-Power=15 dBm   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality=68/70  Signal level=-42 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:997  Invalid misc:26499   Missed beacon:0

lo        no wireless extensions.

But I don’t think that’s the issue as all my devices sitting next to it test at very high speeds.

No, I have dd-wrt on the router and no guest wifi set up.

There are a lot of other wifi networks that show up, but it still doesn’t explain why this laptop is 20 times slower than any other device in the same room.

The commands in the article you linked don’t work. It says it’s an “nc from the netcat-openbsd package”

#4

Okay, the bit rate is a little lower than I would have expected, (I get 72.2Mb/s on my laptop at -50dBm), but 10 times higher than what you report. Again, I wouldn’t rely on internet tests though.

#5

For the netcat LAN speed test, try this instead:

Set up a listening server using

nc -lkv 2222 >/dev/null

At the client laptop do

dd if=/dev/zero bs=1M count=10 | nc -v <server IP address> 2222

and examine the output.

For example, I got the following (both devices connected to my wireless router)

dd if=/dev/zero bs=1M count=10 | nc -v 192.168.1.9 2222
Connection to 192.168.1.9 2222 port [tcp/EtherNet-IP-1] succeeded!
10+0 records in
10+0 records out
10485760 bytes (10 MB) copied, 2.62146 s, 4.0 MB/s

which is of the order I expected.

#6

I get no output at all. And I know the computers can reach each other because when I ping the listener’s IP from the laptop, I get the usual 64 bytes response. What could be wrong with the commands? I typed:

On Desktop:

nc -lkv 2222 >/dev/null

On Laptop:

dd if=/dev/zero bs=1M count=10 | nc -v 192.168.1.137 2222

Then nothing ever happens. After I finally hit ctrl-c, it prints out that 0 bytes were copied.

#7

That will happen if firewalls are active. You need to open port 2222 on the server (Desktop machine in your test), or you could stop the firewall briefly with

systemctl stop  SuSEfirewall2

Now you can run the speed test again.

The firewall can be started again with

systemctl start SuSEfirewall2
#8

It worked! Here’s the (depressing) results:


10+0 records in
10+0 records out
10485760 bytes (10MB) copied, 45.1088 s, 232 KB/s

That is VERY slow. Any suggestions?

#9

That is slow. Perhaps there is some issue with the wireless driver (or at least the interaction with the router).

Confirm which network driver loaded with

/sbin/lspci -nnk|grep '\02' -A3

I think for your wireless network hardware it is the ‘iwlwifi’ module.

You could check for kernel messages related to the driver using one of the commands below

sudo journalctl -b |grep iwlwifi

or

dmesg|grep iwlwifi

Post the output here.

Searching online, I note that others have reported slow network connectivity with this chipset. The last suggestion in this thread might be relevant
http://unix.stackexchange.com/questions/81721/slow-wifi-on-intel-n-6235

What resolved it for me was to enable a setting on my wifi ap.
After enabling WMM/QoS on the router my ubuntu laptop connected with 802.11n(300 - 270Mb/s)

#10

Numerous similar reports from a lot of users running 3.11.10+ kernels. Now, openSUSE is using 4.1.15 by default, but this issue may still be present I guess

http://bernaerts.dyndns.org/linux/74-ubuntu/322-ubuntu-trusty-intel-centrino-6235-slow-freeze

There’s a suggestion to load the iwlwifi driver with options (iwlwifi bt_coex_active=0 swcrypto=1 11n_disable=8)

To solve this performance drop, we need to modify 3 options of iwlwifi module to :

  • Re-enable TX AMPDU aggregation (that was disable by default for iwldvm devices)
  • Disable an advanced technique that tries to minimize interferences between Wifi and Bluetooth signals
  • Disable hardware encryption and use software encryption instead

This will create the custom file in /etc/modprobe.d/directory

echo options iwlwifi bt_coex_active=0 swcrypto=1 11n_disable=8 | sudo tee /etc/modprobe.d/iwlwifi.conf

It will take effect at boot, or just unload the driver and reload with

sudo modprobe -r iwlwifi
sudo modprobe iwlwifi

You could try this and observe whether there is any improvement.

#11

Thank you for helping me with this!

It is and it shows the proper driver: Intel Corporation Centrino Advanced-N 6235 and driver iwlwifi

It outputs:

Apr 02 00:22:12 linux-axi3 kernel: iwlwifi 0000:01:00.0: can't disable ASPM; OS doesn't have ASPM control
Apr 02 00:22:12 linux-axi3 kernel: iwlwifi 0000:01:00.0: loaded firmware version 18.168.6.1 op_mode iwldvm
Apr 02 00:22:12 linux-axi3 kernel: iwlwifi 0000:01:00.0: CONFIG_IWLWIFI_DEBUG enabled
Apr 02 00:22:12 linux-axi3 kernel: iwlwifi 0000:01:00.0: CONFIG_IWLWIFI_DEBUGFS enabled
Apr 02 00:22:12 linux-axi3 kernel: iwlwifi 0000:01:00.0: CONFIG_IWLWIFI_DEVICE_TRACING disabled
Apr 02 00:22:12 linux-axi3 kernel: iwlwifi 0000:01:00.0: Detected Intel(R) Centrino(R) Advanced-N 6235 AGN, REV=0xB0
Apr 02 00:22:12 linux-axi3 kernel: iwlwifi 0000:01:00.0: L1 Enabled - LTR Disabled
Apr 02 00:22:13 linux-axi3 NetworkManager[1001]: <info>  rfkill2: found WiFi radio killswitch (at /sys/devices/pci0000:00/0000:00:1c.0/0000:01:00.0/ieee80211/phy0/rfkill2) (driver iwlwifi)
Apr 02 00:22:13 linux-axi3 NetworkManager[1001]: <info>  (wlan0): new 802.11 WiFi device (carrier: UNKNOWN, driver: 'iwlwifi', ifindex: 2)
Apr 02 00:22:13 linux-axi3 kernel: iwlwifi 0000:01:00.0: L1 Enabled - LTR Disabled
Apr 02 00:22:13 linux-axi3 kernel: iwlwifi 0000:01:00.0: Radio type=0x2-0x1-0x0
Apr 02 00:22:14 linux-axi3 kernel: iwlwifi 0000:01:00.0: L1 Enabled - LTR Disabled
Apr 02 00:22:14 linux-axi3 kernel: iwlwifi 0000:01:00.0: Radio type=0x2-0x1-0x0

I also tried your other suggestion:

But even after restart, that didn’t fix the issue. it was still as slow (the netcat test was 300 Kb/s, so essentially the same).

I really do appreciate all your help! Any other possibilities? Would a USB WiFi adapter work?

Would this work with openSUSE LEAP? http://www.amazon.com/NETGEAR-N900-Wi-Fi-Adapter-WNDA4100/dp/B006V72AE0

#12

I want to use this USB 3.0 WiFi adapter instead of the built in wifi on my laptop with openSUSE LEAP:

http://www.amazon.com/NETGEAR-N900-Wi-Fi-Adapter-WNDA4100/dp/B006V72AE0

I have a Samsung Series 9 with 16 GB RAM, and LEAP installed.

#13

I also tried your other suggestion:
https://forums.opensuse.org/images/misc/quote_icon.png Originally Posted by deano_ferrari https://forums.opensuse.org/images/buttons/viewpost-right.png](https://forums.opensuse.org/showthread.php?p=2772955#post2772955)
This will create the custom file in /etc/modprobe.d/directory
Code:
echo options iwlwifi bt_coex_active=0 swcrypto=1 11n_disable=8 | sudo tee /etc/modprobe.d/iwlwifi.conf

But even after restart, that didn’t fix the issue. it was still as slow (the netcat test was 300 Kb/s, so essentially the same).

That’s unfortunate. Ideally, a kernel bug report is required (assuming there isn’t one describing this issue already).

I really do appreciate all your help! Any other possibilities? Would a USB WiFi adapter work?

Would this work with openSUSE LEAP? http://www.amazon.com/NETGEAR-N900-Wi-Fi-Adapter-WNDA4100/dp/B006V72AE0

I had a quick search, and it seems to be identified as having a Ralink chipset. Many of these devices are now supported by the rt2800usb kernel driver.

For example, one reliable reference:
https://wiki.debian.org/rt2800usb#Supported_Devices

So, yes this device should be okay.

#14

I’ve replied already in your other thread

https://forums.opensuse.org/showthread.php/516894-Is-there-any-special-config-needed-to-use-USB-3-0-WiFi-adapter?p=2772974#post2772974

#15

You’ve posted this question in the wrong forum. I’ll merge it with your existing thread.

#16

I just discovered something! My router has both 2.4 Ghz and 5 Ghz radios. Just to see, I switched to the 5 Ghz connection and the netcat connection went from 300 Kb/s to 5.2 MB/s!! And when I tested the online speedtest (which on 2.4 Ghz was getting a max of 10 mbps down, 5 up) got 80.51 Mbps down, 14 Mbps up!!

I would still like to figure out why the 2.4 Ghz is so terrible on this laptop (using 2.4 on all my other devices gives the SAME speed as 5 Ghz is giving me on this laptop), but at least at home I have a solution. Any ideas what might be causing it to be so terrible on 2.4 Ghz? (It’s 10 feet from the router)

#17

That’s good to know. Use what works I say!

I would still like to figure out why the 2.4 Ghz is so terrible on this laptop (using 2.4 on all my other devices gives the SAME speed as 5 Ghz is giving me on this laptop), but at least at home I have a solution. Any ideas what might be causing it to be so terrible on 2.4 Ghz? (It’s 10 feet from the router)

Only that similar has been reported by many others using this hardware in Linux. Something driver or firmware specific it would seem. You probably need to check out any existing bug reports for this device, and consider adding to them.

#18

Well the 2.4 GHz band is used for everything from wi-fi to some radio remote controllers, the 5GHz band is only used in Japan and depending on your countries laws it’s use might not be legal, that’s the reason for the better speeds the 5GHz has no signal pollution ie. noise from other devices.

#19

Is it worth trying a different channel, if only maybe for the time being or to see what happens?

When I changed AP in the living room, I discovered our new Asus laptop does not like the lower channel numbers (perhaps without a fixed 40Mhz channel width - something I can’t set on this AP) in the 2.4Gh band. The Androids and the old laptop seem OK with such a setting but the Asus becomes painfully slow.

I’ve not tried to diagnose where the problem may be (not even booted to Windows 10 to see if the problem persists) except to say one thing I’m sure - it is not is interference from other wifi (There is only one property that could be in range, I only see 2 other SSIDS anywhere in the house and in the living room these are only just there and both using channels above 6).

It could be that if I want to take the laptop out, I will need to get round to looking further into it and it may even be that I too find myself conssidering a USB adaptor…

But for now at any rate, a simple change to a higher channel does give a workable solution for the 2.4Ghz band at home (although I’ve since got the laptop using the 5Ghz band).

#20

Iv’e just spent some time looking at the Ausus laptop (Realtek 8821AE) in the hope I might stumble on something useful. Not really but I’ll report anyway…

I too had been relying on Internet to work out when things are OK and I guess on my sort of 2.5mbps on a good day connection that’s not much of a test… I have now tried the test using nc given before.

Ch 3 gave me 40KB/s whereas ch 10 gives a bit over 500KBs. A marked improvement but the old laptop (which according to iwconfig connects at 48Mb/s c/f the new one at 150Mb/s) shows 2.6MB/s. As such, I suspect I’m just improving a “bad lot”.

The impression I get from a quick search is that the RTL8821AE is probably a bit new and is under development. I think I’ll invest in a USB adaptor - hopefully dual band and hopefully with some known good record on Linux. It’s probably not a bad accessory to have anyway.