新安装 14.04 后，我无法连接到可用的 wifi 网络（“Bricks and Scones” 是下面日志中的接入点名称）。其他设备（例如我用来发布此内容的 android）连接正常。我不确定我的配置出了什么问题。我查看了系统日志，但仍然无法找出问题所在。这些警告是什么意思？
ryan@palms /v/log> tail -f syslog | grep -C5 'warn\|error'
May 11 18:55:18 palms avahi-daemon[730]: Withdrawing address record for 192.168.1.129 on wlan0.
May 11 18:55:18 palms avahi-daemon[730]: Leaving mDNS multicast group on interface wlan0.IPv4 with address 192.168.1.129.
May 11 18:55:18 palms avahi-daemon[730]: Interface wlan0.IPv4 no longer relevant for mDNS.
May 11 18:55:09 palms whoopsie[1292]: online
May 11 18:55:18 palms whoopsie[1292]: offline
May 11 18:55:18 palms NetworkManager[985]: <warn> DNS: plugin dnsmasq update failed
May 11 18:55:18 palms wpa_supplicant[1004]: nl80211: Was expecting local disconnect but got another disconnect event first
May 11 18:55:18 palms dnsmasq[2269]: setting upstream servers from DBus
May 11 18:55:18 palms NetworkManager[985]: <info> Removing DNS information from /sbin/resolvconf
May 11 18:55:18 palms kernel: [ 806.867681] cfg80211: Calling CRDA to update world regulatory domain
May 11 18:55:18 palms kernel: [ 806.873484] cfg80211: World regulatory domain updated:
--
May 11 18:55:18 palms NetworkManager[985]: <info> Activation (wlan0) starting connection 'Bricks and Scones Guest Network'
May 11 18:55:18 palms NetworkManager[985]: <info> (wlan0): device state change: disconnected -> prepare (reason 'none') [30 40 0]
May 11 18:55:18 palms NetworkManager[985]: <info> NetworkManager state is now CONNECTING
May 11 18:55:18 palms NetworkManager[985]: <info> Activation (wlan0) Stage 1 of 5 (Device Prepare) scheduled...
May 11 18:55:18 palms wpa_supplicant[1004]: wlan0: CTRL-EVENT-SCAN-STARTED
May 11 18:55:18 palms NetworkManager[985]: <warn> Connection disconnected (reason -3)
May 11 18:55:18 palms NetworkManager[985]: <info> (wlan0): supplicant interface state: completed -> disconnected
May 11 18:55:18 palms NetworkManager[985]: <info> Activation (wlan0) Stage 1 of 5 (Device Prepare) started...
May 11 18:55:18 palms NetworkManager[985]: <info> Activation (wlan0) Stage 2 of 5 (Device Configure) scheduled...
May 11 18:55:18 palms NetworkManager[985]: <info> Activation (wlan0) Stage 1 of 5 (Device Prepare) complete.
May 11 18:55:18 palms NetworkManager[985]: <info> Activation (wlan0) Stage 2 of 5 (Device Configure) starting...
--
May 11 18:55:39 palms NetworkManager[985]: <info> Activation (wlan0) Stage 4 of 5 (IPv6 Configure Timeout) started...
May 11 18:55:39 palms NetworkManager[985]: <info> Activation (wlan0) Stage 4 of 5 (IPv6 Configure Timeout) complete.
May 11 18:55:40 palms dhclient: DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 10 (xid=0x7609df84)
May 11 18:55:50 palms dhclient: DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 13 (xid=0x7609df84)
May 11 18:56:03 palms dhclient: DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 9 (xid=0x7609df84)
May 11 18:56:04 palms NetworkManager[985]: <warn> (wlan0): DHCPv4 request timed out.
May 11 18:56:04 palms NetworkManager[985]: <info> (wlan0): canceled DHCP transaction, DHCP client pid 4231
May 11 18:56:04 palms NetworkManager[985]: <info> Activation (wlan0) Stage 4 of 5 (IPv4 Configure Timeout) scheduled...
May 11 18:56:04 palms NetworkManager[985]: <info> Activation (wlan0) Stage 4 of 5 (IPv4 Configure Timeout) started...
May 11 18:56:04 palms NetworkManager[985]: <info> (wlan0): device state change: ip-config -> failed (reason 'ip-config-unavailable') [70 120 5]
May 11 18:56:04 palms NetworkManager[985]: <info> NetworkManager state is now DISCONNECTED
May 11 18:56:04 palms NetworkManager[985]: <info> Marking connection 'Bricks and Scones Guest Network' invalid.
May 11 18:56:04 palms NetworkManager[985]: <warn> Activation (wlan0) failed for connection 'Bricks and Scones Guest Network'
May 11 18:56:04 palms NetworkManager[985]: <info> Activation (wlan0) Stage 4 of 5 (IPv4 Configure Timeout) complete.
May 11 18:56:04 palms NetworkManager[985]: <info> (wlan0): device state change: failed -> disconnected (reason 'none') [120 30 0]
May 11 18:56:04 palms NetworkManager[985]: <info> (wlan0): deactivating device (reason 'none') [0]
May 11 18:56:04 palms avahi-daemon[730]: Withdrawing address record for fe80::3623:87ff:fefd:5b57 on wlan0.
May 11 18:56:04 palms avahi-daemon[730]: Leaving mDNS multicast group on interface wlan0.IPv6 with address fe80::3623:87ff:fefd:5b57.
May 11 18:56:04 palms avahi-daemon[730]: Interface wlan0.IPv6 no longer relevant for mDNS.
May 11 18:56:04 palms wpa_supplicant[1004]: wlan0: CTRL-EVENT-DISCONNECTED bssid=7e:d1:c3:ce:2c:9a reason=3 locally_generated=1
May 11 18:56:04 palms NetworkManager[985]: <warn> Connection disconnected (reason -3)
May 11 18:56:04 palms wpa_supplicant[1004]: wlan0: CTRL-EVENT-SCAN-STARTED
May 11 18:56:04 palms wpa_supplicant[1004]: nl80211: Was expecting local disconnect but got another disconnect event first
May 11 18:56:04 palms NetworkManager[985]: <info> (wlan0): supplicant interface state: completed -> disconnected
May 11 18:56:04 palms kernel: [ 852.988624] cfg80211: Calling CRDA to update world regulatory domain
May 11 18:56:04 palms kernel: [ 852.991920] cfg80211: World regulatory domain updated:
（较长的一段在这里：http://pastebin.com/EPbp51Dz）
答案1
虽然有点牵强，但你的日志中有与一篇发表在 zeroset 博客上。他的（也是我的）问题是，一些适配器和接入点在 N 模式下交互不良。解决方法是禁用 N 模式，然后切换到较慢的模式。
从您的日志来看，您似乎没有英特尔适配器，但如果有，您可以尝试 zeroset 的解决方案：
临时解决方案
对于临时解决方案，例如检查建议的解决方案是否有助于您的设置，请重新加载无线上网带选项的内核模块 11n_disable设置为 1，以禁用 802.11N，例如通过
sudo sh -c 'modprobe -r iwlwifi && modprobe iwlwifi 11n_disable=1'由于您需要 root 权限才能重新加载内核模块，因此系统会要求您输入 sudo 密码。
永久解决方案
要在驱动程序中永久禁用 802.11N，请添加以下行
options iwlwifi 11n_disable=1到
/etc/modprobe.d/iwlwifi.conf
这里的“临时”意味着一旦重新启动它就会恢复。
有时你必须先禁用 802.11N（如上所示），然后重新启用它才能解决问题
答案2
我遇到了类似的问题，但是不设备无法连接，即使使用以太网也是如此。我在这里提供解决方案，因为这是错误消息的顶级谷歌搜索结果。
我修复了这个问题关闭路由器并重新打开。
因此，对于像我这样的聪明人来说，开始通过他们的日志来诊断问题，然后查看Connection disconnected (reason -3)，还没有尝试重新启动路由器...在谷歌搜索之前先执行此操作。