NM fails to connect to campus Wi-Fi network; wicd succeeds -- Centrino Ultimate-N 6300 iwlwifi

[Ross Schlaikjer]

The iwlwifi drivers give exceptional performance on all APs I have connected to, be they WEP, WPA or open. The only time this system lets me down is when connecting to my campus wireless network. NetworkManager will only sometimes connect, and even manually configuring with iwconfig does not always work.

The error usually given is either:

Jan 30 01:07:51 Beast kernel: [ 8777.748471] wlan0: direct probe to 00:1a:1e:a0:3b:c0 (try 1/3)
Jan 30 01:07:51 Beast kernel: [ 8777.945384] wlan0: direct probe to 00:1a:1e:a0:3b:c0 (try 2/3)
Jan 30 01:07:51 Beast kernel: [ 8778.144952] wlan0: direct probe to 00:1a:1e:a0:3b:c0 (try 3/3)
Jan 30 01:07:52 Beast kernel: [ 8778.344474] wlan0: direct probe to 00:1a:1e:a0:3b:c0 timed out

or:

Nov 30 19:01:27 Beast kernel: [ 1924.850725] wlan0: authenticate with 00:24:6c:60:d0:00 (try 1)
Nov 30 19:01:27 Beast kernel: [ 1924.852183] wlan0: 00:24:6c:60:d0:00 denied authentication (status 17)

Other people report that this error may be linked to MAC filtering by the AP, but this should not be the case: my old computer with a Broadcom BCM4312 had no trouble.

This bug is also different from several bug reports that complain of limited speed or packet loss: when I can connect, the connection is flawless. But very often I cannot connecct. The connection is generally worse in crowded areas, or areas with many access points.

lspci:
Network controller [0280]: Intel Corporation Centrino Ultimate-N 6300 [8086:4238] (rev 3e)

ifconfig wlan0:
wlan0 Link encap:Ethernet HWaddr 24:77:03:26:e8:50
          inet addr:130.64.153.137 Bcast:130.64.153.255 Mask:255.255.255.0
          inet6 addr: fe80::2677:3ff:fe26:e850/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:1288307 errors:0 dropped:0 overruns:0 frame:0
          TX packets:296448 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1016044127 (1.0 GB) TX bytes:27674773 (27.6 MB)

 iwconfig wlan0:
wlan0 IEEE 802.11abgn ESSID:"tuftswireless"
          Mode:Managed Frequency:5.785 GHz Access Point: 00:24:6C:60:D0:10
          Bit Rate=300 Mb/s Tx-Power=15 dBm
          Retry long limit:7 RTS thr:off Fragment thr:off
          Power Management:off
          Link Quality=61/70 Signal level=-49 dBm
          Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
          Tx excessive retries:2749 Invalid misc:7 Missed beacon:0

lsmod | grep iw:
iwlwifi 320164 0
mac80211 506154 1 iwlwifi
cfg80211 209294 2 iwlwifi,mac80211

dmesg | grep wlan:

[ 12.059405] wlan0: direct probe to 00:24:6c:60:d0:00 (try 1/3)
[ 12.258109] wlan0: direct probe to 00:24:6c:60:d0:00 (try 2/3)
[ 12.457695] wlan0: direct probe to 00:24:6c:60:d0:00 (try 3/3)
[ 12.657205] wlan0: direct probe to 00:24:6c:60:d0:00 timed out
[ 20.624778] wlan0: direct probe to 00:24:6c:60:d0:00 (try 1/3)
[ 20.822683] wlan0: direct probe to 00:24:6c:60:d0:00 (try 2/3)
[ 21.022217] wlan0: direct probe to 00:24:6c:60:d0:00 (try 3/3)
[ 21.221788] wlan0: direct probe to 00:24:6c:60:d0:00 timed out
[ 29.105117] wlan0: direct probe to 00:24:6c:60:d0:00 (try 1/3)
[ 29.303463] wlan0: direct probe to 00:24:6c:60:d0:00 (try 2/3)
[ 29.503007] wlan0: direct probe to 00:24:6c:60:d0:00 (try 3/3)
[ 29.702581] wlan0: direct probe to 00:24:6c:60:d0:00 timed out
[ 37.888734] wlan0: direct probe to 00:24:6c:60:d0:00 (try 1/3)
[ 38.087513] wlan0: direct probe to 00:24:6c:60:d0:00 (try 2/3)
[ 38.287083] wlan0: direct probe to 00:24:6c:60:d0:00 (try 3/3)
[ 38.486602] wlan0: direct probe to 00:24:6c:60:d0:00 timed out
[ 46.376942] wlan0: authenticate with 00:24:6c:60:d0:00 (try 1)
[ 46.411091] wlan0: 00:24:6c:60:d0:00 denied authentication (status 17)

syslog:

Nov 30 19:01:27 Beast kernel: [ 1924.850725] wlan0: authenticate with 00:24:6c:60:d0:00 (try 1)
Nov 30 19:01:27 Beast kernel: [ 1924.852183] wlan0: 00:24:6c:60:d0:00 denied authentication (status 17)
Nov 30 19:02:24 Beast NetworkManager[1332]: <warn> Activation (wlan0/wireless): association took too long, failing activation.
Nov 30 19:02:24 Beast NetworkManager[1332]: <info> (wlan0): device state change: config -> failed (reason 'supplicant-timeout') [50 120 11]
Nov 30 19:02:24 Beast NetworkManager[1332]: <warn> Activation (wlan0) failed for access point (tuftswireless)
Nov 30 19:02:24 Beast NetworkManager[1332]: <warn> Activation (wlan0) failed.
Nov 30 19:02:24 Beast NetworkManager[1332]: <info> (wlan0): device state change: failed -> disconnected (reason 'none') [120 30 0]
Nov 30 19:02:24 Beast NetworkManager[1332]: <info> (wlan0): deactivating device (reason 'none') [0]
Nov 30 19:02:24 Beast NetworkManager[1332]: <info> (wlan0): supplicant interface state: authenticating -> disconnected
Nov 30 19:02:24 Beast NetworkManager[1332]: <warn> Couldn't disconnect supplicant interface: This interface is not connected.
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> Auto-activating connection 'Auto hpsetup'.
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> Activation (wlan0) starting connection 'Auto hpsetup'
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> (wlan0): device state change: disconnected -> prepare (reason 'none') [30 40 0]
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> Activation (wlan0) Stage 1 of 5 (Device Prepare) scheduled...
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> Activation (wlan0) Stage 1 of 5 (Device Prepare) started...
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> Activation (wlan0) Stage 2 of 5 (Device Configure) scheduled...
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> Activation (wlan0) Stage 1 of 5 (Device Prepare) complete.
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> Activation (wlan0) Stage 2 of 5 (Device Configure) starting...
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> (wlan0): device state change: prepare -> config (reason 'none') [40 50 0]
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> Activation (wlan0/wireless): connection 'Auto hpsetup' requires no security. No secrets needed.
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> Config: added 'ssid' value 'tuftswireless'
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> Config: added 'scan_ssid' value '1'
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> Config: added 'key_mgmt' value 'NONE'
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> Activation (wlan0) Stage 2 of 5 (Device Configure) complete.
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> Config: set interface ap_scan to 1
Nov 30 19:02:27 Beast NetworkManager[1332]: <info> (wlan0): supplicant interface state: disconnected -> scanning
Nov 30 19:02:30 Beast wpa_supplicant[6090]: Trying to authenticate with 00:24:6c:60:d0:00 (SSID='tuftswireless' freq=2437 MHz)
Nov 30 19:02:30 Beast NetworkManager[1332]: <info> (wlan0): supplicant interface state: scanning -> authenticating
Nov 30 19:02:30 Beast kernel: [ 1987.684183] wlan0: authenticate with 00:24:6c:60:d0:00 (try 1)
Nov 30 19:02:30 Beast kernel: [ 1987.687421] wlan0: 00:24:6c:60:d0:00 denied authentication (status 17)

sudo iwlist scan:

wlan0 Scan completed :
          Cell 01 - Address: 00:24:6C:60:D0:10
                    Channel:157
                    Frequency:5.785 GHz
                    Quality=57/70 Signal level=-53 dBm
                    Encryption key:off
                    ESSID:"tuftswireless"
                    Bit Rates:12 Mb/s; 18 Mb/s; 24 Mb/s; 36 Mb/s; 48 Mb/s
                              54 Mb/s
                    Mode:Master
                    Extra:tsf=0000005a132e5c6a
                    Extra: Last beacon: 76ms ago
                    IE: Unknown: 000D7475667473776972656C657373
                    IE: Unknown: 010698243048606C
                    IE: Unknown: 03019D
                    IE: Unknown: 2D1A4E001BFFFF000000000000000000000000000000000000000000
                    IE: Unknown: 3D169D051B000000FF000000000000000000000000000000
                    IE: Unknown: DD1E00904C334E001BFFFF000000000000000000000000000000000000000000
                    IE: Unknown: DD1A00904C349D051B000000FF000000000000000000000000000000
                    IE: Unknown: DD180050F2020101800003A4000027A4000042435E0062322F00
                    IE: Unknown: DD0A00037F04010000000000
          Cell 02 - Address: 00:0B:86:58:19:A0
                    Channel:1
                    Frequency:2.412 GHz (Channel 1)
                    Quality=39/70 Signal level=-71 dBm
                    Encryption key:off
                    ESSID:"tuftswireless"
                    Bit Rates:2 Mb/s; 6 Mb/s; 9 Mb/s; 11 Mb/s; 12 Mb/s
                              18 Mb/s; 24 Mb/s; 36 Mb/s
                    Bit Rates:48 Mb/s; 54 Mb/s
                    Mode:Master
                    Extra:tsf=0000000202533181
                    Extra: Last beacon: 9104ms ago
                    IE: Unknown: 000D7475667473776972656C657373
                    IE: Unknown: 0108840C121618243048
                    IE: Unknown: 030101
                    IE: Unknown: 2A0100
                    IE: Unknown: 3202606C
                    IE: Unknown: DD180050F2020101800003A4000027A4000042435E0062322F00
                    IE: Unknown: DD0A00037F04010000000000
          Cell 03 - Address: 00:24:6C:60:CF:A0
                    Channel:6
                    Frequency:2.437 GHz (Channel 6)
                    Quality=50/70 Signal level=-60 dBm
                    Encryption key:off
                    ESSID:"tuftswireless"
                    Bit Rates:2 Mb/s; 11 Mb/s; 6 Mb/s; 9 Mb/s; 12 Mb/s
                              18 Mb/s; 24 Mb/s; 36 Mb/s
                    Bit Rates:48 Mb/s; 54 Mb/s
                    Mode:Master
                    Extra:tsf=0000000c808e35af
                    Extra: Last beacon: 8704ms ago
                    IE: Unknown: 000D7475667473776972656C657373
                    IE: Unknown: 010884160C1218243048
                    IE: Unknown: 030106
                    IE: Unknown: 050400010100
                    IE: Unknown: 2A0100
                    IE: Unknown: 3202606C
                    IE: Unknown: 2D1A4C101BFFFF000000000000000000000000000000000000000000
                    IE: Unknown: 3D1606001B000000FF000000000000000000000000000000
                    IE: Unknown: DD1E00904C334C101BFFFF000000000000000000000000000000000000000000
                    IE: Unknown: DD1A00904C3406001B000000FF000000000000000000000000000000
                    IE: Unknown: DD180050F2020101800003A4000027A4000042435E0062322F00
                    IE: Unknown: DD0A00037F04010000000000
          Cell 04 - Address: 00:0B:86:58:1F:A0
                    Channel:11
                    Frequency:2.462 GHz (Channel 11)
                    Quality=38/70 Signal level=-72 dBm
                    Encryption key:off
                    ESSID:"tuftswireless"
                    Bit Rates:2 Mb/s; 11 Mb/s; 6 Mb/s; 9 Mb/s; 12 Mb/s
                              18 Mb/s; 24 Mb/s; 36 Mb/s
                    Bit Rates:48 Mb/s; 54 Mb/s
                    Mode:Master
                    Extra:tsf=00000006687da181
                    Extra: Last beacon: 7328ms ago
                    IE: Unknown: 000D7475667473776972656C657373
                    IE: Unknown: 010884160C1218243048
                    IE: Unknown: 03010B
                    IE: Unknown: 050400010180
                    IE: Unknown: 2A0102
                    IE: Unknown: 3202606C
                    IE: Unknown: DD180050F2020101800003A4000027A4000042435E0062322F00
                    IE: Unknown: DD0A00037F04010000000000
          Cell 05 - Address: 00:24:6C:60:CF:B0
                    Channel:36
                    Frequency:5.18 GHz (Channel 36)
                    Quality=41/70 Signal level=-69 dBm
                    Encryption key:off
                    ESSID:"tuftswireless"
                    Bit Rates:12 Mb/s; 18 Mb/s; 24 Mb/s; 36 Mb/s; 48 Mb/s
                              54 Mb/s
                    Mode:Master
                    Extra:tsf=0000002e94c969ed
                    Extra: Last beacon: 7072ms ago
                    IE: Unknown: 000D7475667473776972656C657373
                    IE: Unknown: 010698243048606C
                    IE: Unknown: 030124
                    IE: Unknown: 2D1A4E001BFFFF000000000000000000000000000000000000000000
                    IE: Unknown: 3D1624050A000000FF000000000000000000000000000000
                    IE: Unknown: DD1E00904C334E001BFFFF000000000000000000000000000000000000000000
                    IE: Unknown: DD1A00904C3424050A000000FF000000000000000000000000000000
                    IE: Unknown: DD180050F2020101800003A4000027A4000042435E0062322F00
                    IE: Unknown: DD0A00037F04010000000000
          Cell 06 - Address: 00:0B:86:59:FD:C8
                    Channel:40
                    Frequency:5.2 GHz (Channel 40)
                    Quality=31/70 Signal level=-79 dBm
                    Encryption key:off
                    ESSID:"tuftswireless"
                    Bit Rates:12 Mb/s; 18 Mb/s; 24 Mb/s; 36 Mb/s; 48 Mb/s
                              54 Mb/s
                    Mode:Master
                    Extra:tsf=0000005a137c235f
                    Extra: Last beacon: 6560ms ago
                    IE: Unknown: 000D7475667473776972656C657373
                    IE: Unknown: 010698243048606C
                    IE: Unknown: 030128
                    IE: Unknown: DD180050F2020101800003A4000027A4000042435E0062322F00
                    IE: Unknown: DD0A00037F04010000000000
          Cell 07 - Address: 00:24:6C:60:D5:50
                    Channel:44
                    Frequency:5.22 GHz (Channel 44)
                    Quality=37/70 Signal level=-73 dBm
                    Encryption key:off
                    ESSID:"tuftswireless"
                    Bit Rates:12 Mb/s; 18 Mb/s; 24 Mb/s; 36 Mb/s; 48 Mb/s
                              54 Mb/s
                    Mode:Master
                    Extra:tsf=0000005a1328778d
                    Extra: Last beacon: 6336ms ago
                    IE: Unknown: 000D7475667473776972656C657373
                    IE: Unknown: 010698243048606C
                    IE: Unknown: 03012C
                    IE: Unknown: 2D1A4E001BFFFF000000000000000000000000000000000000000000
                    IE: Unknown: 3D162C0508000000FF000000000000000000000000000000
                    IE: Unknown: DD1E00904C334E001BFFFF000000000000000000000000000000000000000000
                    IE: Unknown: DD1A00904C342C0508000000FF000000000000000000000000000000
                    IE: Unknown: DD180050F2020101800003A4000027A4000042435E0062322F00
                    IE: Unknown: DD0A00037F04010000000000
          Cell 08 - Address: 00:0B:86:58:1F:A8
                    Channel:48
                    Frequency:5.24 GHz (Channel 48)
                    Quality=34/70 Signal level=-76 dBm
                    Encryption key:off
                    ESSID:"tuftswireless"
                    Bit Rates:12 Mb/s; 18 Mb/s; 24 Mb/s; 36 Mb/s; 48 Mb/s
                              54 Mb/s
                    Mode:Master
                    Extra:tsf=0000005a13a8e1c3
                    Extra: Last beacon: 6124ms ago
                    IE: Unknown: 000D7475667473776972656C657373
                    IE: Unknown: 010698243048606C
                    IE: Unknown: 030130
                    IE: Unknown: DD180050F2020101800003A4000027A4000042435E0062322F00
                    IE: Unknown: DD0A00037F04010000000000
          Cell 09 - Address: 00:24:6C:60:CF:F0
                    Channel:149
                    Frequency:5.745 GHz
                    Quality=37/70 Signal level=-73 dBm
                    Encryption key:off
                    ESSID:"tuftswireless"
                    Bit Rates:12 Mb/s; 18 Mb/s; 24 Mb/s; 36 Mb/s; 48 Mb/s
                              54 Mb/s
                    Mode:Master
                    Extra:tsf=0000005a131955bb
                    Extra: Last beacon: 764ms ago
                    IE: Unknown: 000D7475667473776972656C657373
                    IE: Unknown: 010698243048606C
                    IE: Unknown: 030195
                    IE: Unknown: 2D1A4E001BFFFF000000000000000000000000000000000000000000
                    IE: Unknown: 3D16950508000000FF000000000000000000000000000000
                    IE: Unknown: DD1E00904C334E001BFFFF000000000000000000000000000000000000000000
                    IE: Unknown: DD1A00904C34950508000000FF000000000000000000000000000000
                    IE: Unknown: DD180050F2020101800003A4000027A4000042435E0062322F00
                    IE: Unknown: DD0A00037F04010000000000

lsb_release -d:
Description: Ubuntu 11.10

uname -a:
Linux Beast 3.0.0-13-generic #22-Ubuntu SMP Wed Nov 2 13:27:26 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux

[Mathieu Trudel-Lapierre (cyphermox)]

Thank you for filing this bug report and helping to make Ubuntu better.

Your syslog excerpt explains precisely why the connection times out and authentication is denied while trying to connect: there's an error response from the accesspoint, in the form of the "status 17" message.

I understand this is quite cryptic. Status 17 is defined as "Association denied because AP is unable to handle additional associated STAs" in the IEEE 802.11-2007 standard. I basically means that the authentication was denied because the accesspoint cannot handle additional "stations" to be connected to it. Stations are any wireless client that might try to connect.

As a solution, the best I can offer is to suggest you contact your network's administrators and point to this bug report as an additional indication that the network is crowded.

Closing as Invalid since it's not a bug in Ubuntu.

Please, don't hesitate to report bugs for any further issues you may find! :)

[Ross Schlaikjer (ross-schlaikjer)]

The only thing is - this is a problem in network-manager. My previous network card had no trouble, and having installed wicd I have never seen this problem. I don't think that this is an overcrowding issue, and that there is still an issue with network-manager.

[Mathieu Trudel-Lapierre (cyphermox)]

Sorry -- there's just really nothing in that bug report that supports this. If you can, please test with a different card or whatnot, but there's still no reason to believe a success might then be because it's the different card. Didn't you mention you sometimes successfully connect?

Stating the description: "when I can connect, the connection is flawless. But very often I cannot. The connection is generally worse in crowded areas, or areas with many access points."

With the additional information that it's usually worse in crowded areas or when there are many access points (many access points is generally indicative that the area may be crowded to a point that multiple APs are required to support all the clients), it's further evidence that this is just contention on the AP side.

There are however known problems with N on this kind of card, so I guess it's technically possible you'd be seeing a different side-effect of the performance issues with N -- but you also mentioned this was different from the other performance-related bug reports.

Finally, this being the only network where you reportedly encounter this particular issue, there is again then no evidence to suggest it's not environment-related.

I'm willing to consider this might be a bug in NM, but those would normally affect all wireless networks indiscriminately considering NM only asks the kernel via wpasupplicant to establish connections and does minimal house-keeping for the connection. Everything else is done by the kernel.

I'll reset this to Incomplete. Please see if you can provide further information that would point this clearly in the direction of a software bug.

[Ross Schlaikjer (ross-schlaikjer)]

When I was using network-manager, I could connect fine to every network except the campus network, which is composed of a ton of APs everywhere. When trying to connect to the campus network I would usually get the following:
[ 12.059405] wlan0: direct probe to 00:24:6c:60:d0:00 (try 1/3)
[ 12.258109] wlan0: direct probe to 00:24:6c:60:d0:00 (try 2/3)
[ 12.457695] wlan0: direct probe to 00:24:6c:60:d0:00 (try 3/3)
[ 12.657205] wlan0: direct probe to 00:24:6c:60:d0:00 timed out

This was a much more common error than status 17. After displaying this message, nm-applet would show the connecting icon until something timed out. Periodically it could connect, but would usually drop the connection.

The fact that after replacing nm with wicd completely resolved the problem leads me to believe that it was a bug in nm, and not a hardware problem - under Win7 and now with wicd, there are zero connection issues.

[pcsrule (pcsrule)]

I can confirm this bug. I have an intel advanced N 6320 card and I get the same direct probe failure messages on my campus wifi. The network works fine in windows and on my phone/tablet, but I cannot connect when using network-manager. I'll try wicd as suggested to confirm the issue is in network-manager.

[Simone Bianco (newcolour78)]

This bug affects me too. Can anybody confirm that wicd solves the problem?

Cheers,
S.

[Ross Schlaikjer (ross-schlaikjer)]

I can confirm that switching to WICD fixes the problem for me partially - I see a large number of APs for the same SSID, and can always connect to at least one of them.

[Bobby Graese (bobby-graese)]

I've been experiencing this same problem on my campus network for a while, and switching to WICD seems to have fixed it for me, too!

I think it's worth noting that the access points on my campus are Aruba Networks access points, and we use the SafeConnect system for network authentication. We actually run two networks: the campus network, and a guest network. The guest network bypasses authentication through SafeConnect to allow guests to hop on the campus wireless (with some access restrictions). I have never had any trouble connecting to the guest network with NetworkManager, but almost always got the "Status 17" error when connecting to the campus network.

I've attempted to research this issue before, and seem to recall something about this being specific to Aruba Networks access points. http://ubuntuforums.org/showthread.php?t=1889157 seems to make that connection, and points to a bug filed with the intel wireless drivers: http://bugzilla.intellinuxwireless.org/show_bug.cgi?id=2346 .

In any case, WICD does seem to work as a workaround!

[Till W. (tillw.)]

I am suffering from the same problem. My NIC is an Intel 6205:

03:00.0 Network controller: Intel Corporation Centrino Advanced-N 6205 (rev 34)
 Subsystem: Intel Corporation Centrino Advanced-N 6205 AGN
 Flags: bus master, fast devsel, latency 0, IRQ 49
 Memory at f2500000 (64-bit, non-prefetchable) [size=8K]
 Capabilities: <access denied>
 Kernel driver in use: iwlwifi
 Kernel modules: iwlwifi

My observations are:

Almost all WiFi networks work flawless using NetworkManager. However, with some networks I have persistent problems. I get a connection for a few minutes following boot-up, after that the NetworkManager icon goes to "scanning" and the syslog fllls up with "direct probe timed out messages. I experience this problem *only* in my university. They use exclusively Cisco equipment. I can look up the access point models if necessary.

I am rather sure that NetworkManager is part of the problem. I experience the problem even when trying to connect to an unencrypted network at my university. However, when I stop NetworkManager and connect manually (iwconfig wlan0 essid FOO; ifconfig wlan0 up; dhclient wlan0) the bug does not occur even after hours.

I also tried "iwconfig wlan0 power off" but this does not fix the "direct probe timeout" problem.

[ryan porto (ryan-porto)]

Please help, I am having the exact same problem. I too have the Intel 6300 card, and everything works flawlessly when on my home router, however, I have the same issue while at school. I have disabled wireless n as well as power management, please help.

[Andrew Skalski (askalski)]

I have a Dell Precision M4600 with Ultimate-N 6300 (rev 35), and have had this sort of problem for quite some time. It generally happens with networks where there are many access points, and many people connecting to the network (at work, at hotels, etc.)

A workaround which has been reliable in getting me connected to the wireless network at work is to run this script in a terminal window while NM is trying to associate with the network. For whatever reason, running "iwconfig wlan0 essid WhateverSSID" at the right moment during association makes it succeed for me. (On the other hand, it sometimes causes a kernel NULL pointer derefernce in __cfg80211_mlme_deauth, which means I have to hard-shutdown the machine.) I would be interested in knowing if this script helps anybody else.

#! /bin/bash

connection_id="The SSID of your network"
interface="wlan0"
polls=90
interval=1

change_status() {
        tput dl1
        tput cr
        echo "$1"
}

check_connection() {
        if nmcli con status id $1 | grep -q '^GENERAL.STATE:.*activated'
        then
                change_status Activated
                exit 0
        fi
}

check_connection "$connection_id"
for (( i = 1; i <= $polls; i++ ))
do
        echo -n .
        sudo iwconfig "$interface" essid "$connection_id"
        sleep "$interval"
        check_connection "$connection_id"
done

change_status '???'
exit 1

[hangelwen (hangelwen)]

I have the same problem for more than one year. Sometime I even felt a little disappointed about Linux (This not only happened under Ubuntu, It happened under some other distributions too, for example, Arch), especially when I was having a meeting and wanting to show something to the professor over ssh: the network just dropped out every minutes or just can not connect.

Back to about two years ago, I used Ubuntu 10.04, there is no this problem. I switched to then newer 11.04 because of a problem with the display card driver, then this problem started to occur. I goggled and tried every workaround I found (I even bought a new network card), no one can completely solve the problem. I can connect to my home network without a problem, but when came to the campus network, many problems happened: I can connect to it in my office with several dropouts a day. I can not connect to it or the network dropped out every minutes when I was in a professors office, which is in the same building but on a different floor, and can not connect to it in the library in the same building . I kept installing new versions of Ubuntu and upgraded to new kernels, but the problem is still here.

From the output of dmesg, I noticed that there were usually two cases: 1. authentication timed out. 2. deauthenticated from the network quickly after a successful connection by local choice with reason number either 2 or 3.

I don't think this is overcrowd related, because Windows works, iOS works, and even wicd works(not perfectly). And this also happens on another Ubuntu laptop of one of my office mates.

[Andrew Skalski (askalski)]

This issue no longer affects me. The problem went away when two changes were made to the wireless network over the span of about a week. I don't know which change actually fixed it, but I suspect it was the second of the two:

One change was updating the firmware on the access points.

In the other, a misconfiguration was corrected where DHCP was issuing gateway addresses outside of the subnet.