[ltp] T400 slow wifi connections

[Paul Marwick]

Joerg Mayer wrote:
> On Sat, Sep 14, 2013 at 01:23:50AM +0100, Paul Marwick wrote:
>> I'm running a T400 (6474-AH5). I've recently upgraded my router to
>> an Asus RT-N56U (running Padavan firmware). With two different Linux
>> distributions, I get consistent 150 mb/s connections to the 5 GHz AP
>> in the router, and consistent 72.5 mb/s connections to the 2.4 GHz
>> AP.
>>
>> The Linux distros are Arch (3.10.10-1-ARCH #1 SMP PREEMPT) and
>> SolydX (3.9.2 or 3.10.2 kernel).
>>
>> Under Windows 7, I'm getting consistent 270 or 280 mb/s connections
>> to the same 5 GHz AP.
>>
>> The wifi card in the T400 is Intel PRO/Wireless 5100 AGN [Shiloh]
>> Network Connection.
> So the Windows througput should be very close to the therorectical
> receive maximum for the 5100. Maximum transmit should be half that.

That was one of the things that struck me - it looks as though my 
connect speeds are around half the maximum.
>
> Can you please post the output of the following commands:
>
> iw reg get

country GB: DFS-UNSET
(2402 - 2482 @ 40), (N/A, 20)
(5170 - 5250 @ 40), (N/A, 20)
(5250 - 5330 @ 40), (N/A, 20), DFS
(5490 - 5710 @ 40), (N/A, 27), DFS
(57240 - 65880 @ 2160), (N/A, 40), NO-OUTDOOR

> iw dev wlan0 info

Interface wlan0
ifindex 3
wdev 0x1
addr 00:1e:65:19:f9:be
ssid ASUS_5G
type managed
wiphy 0
channel 36 (5180 MHz), width: 40 MHz, center1: 5190 MHz


> iw dev wlan0 scan -u (only paste the data for your SSID)

BSS 10:bf:48:3c:df:b0(on wlan0) -- associated
     TSF: 2266987624311 usec (26d, 05:43:07)
     freq: 5180
     beacon interval: 100 TUs
     capability: ESS Privacy (0x0011)
     signal: -35.00 dBm
     last seen: 93 ms ago
     Information elements from Probe Response frame:
     SSID: ASUS_5G
     Supported rates: 6.0* 9.0 12.0* 18.0 24.0* 36.0 48.0 54.0
     DS Parameter set: channel 36
     Unknown IE (60): 01 16 24 00
     HT capabilities:
         Capabilities: 0x1ee
             HT20/HT40
             SM Power Save disabled
             RX HT20 SGI
             RX HT40 SGI
             TX STBC
             RX STBC 1-stream
             Max AMSDU length: 3839 bytes
             No DSSS/CCK HT40
         Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
         Minimum RX AMPDU time spacing: 4 usec (0x05)
         HT RX MCS rate indexes supported: 0-23, 32
         HT TX MCS rate indexes are undefined
     HT operation:
          * primary channel: 36
          * secondary channel offset: above
          * STA channel width: any
          * RIFS: 0
          * HT protection: no
          * non-GF present: 0
          * OBSS non-GF present: 0
          * dual beacon: 0
          * dual CTS protection: 0
          * STBC beacon: 0
          * L-SIG TXOP Prot: 0
          * PCO active: 0
          * PCO phase: 0
     Secondary Channel Offset: no secondary (0)
     RSN:     * Version: 1
          * Group cipher: CCMP
          * Pairwise ciphers: CCMP
          * Authentication suites: PSK
          * Capabilities: (0x0000)
     WMM:     * Parameter version 1
          * BE: CW 15-1023, AIFSN 3
          * BK: CW 15-1023, AIFSN 7
          * VI: CW 7-15, AIFSN 2, TXOP 3008 usec
          * VO: CW 3-7, AIFSN 2, TXOP 1504 usec
     BSS Load:
          * station count: 0
          * channel utilisation: 1/255
          * available admission capacity: 31250 [*32us]
     Vendor specific: OUI 00:0c:43, data: 07 00 00 00
     Country: GB    Environment: Indoor/Outdoor
         Channels [36 - 48] @ 16 dBm


>
> Thanks
>      Jörg
:) Thank you. Those were all taken under Arch.

Paul.