我刚刚将我的 Dell Inspiron 从 ubuntu trusty 升级到 xubuntu wily（我格式化并执行了全新安装，而不是通常的升级）。除了移动宽带（ppp0），其他一切都正常工作。奇怪的是，当我运行实时 CD 时，加密狗（华为）工作正常，但在我的安装中，加密狗连接了，但我无法浏览互联网。这是我在移动宽带上建立连接时的系统日志输出：
Apr 19 16:01:32 phoenix NetworkManager[811]: <info> devices added (path: /sys/devices/virtual/net/ppp0, iface: ppp0)
Apr 19 16:01:32 phoenix NetworkManager[811]: <info> device added (path: /sys/devices/virtual/net/ppp0, iface: ppp0): no ifupdown configuration found.
Apr 19 16:01:32 phoenix NetworkManager[811]: nm-pppd-plugin-Message: nm-ppp-plugin: (get_credentials): passwd-hook, requesting credentials...
Apr 19 16:01:32 phoenix NetworkManager[811]: nm-pppd-plugin-Message: nm-ppp-plugin: (get_credentials): got credentials from NetworkManager
Apr 19 16:01:32 phoenix pppd[5970]: CHAP authentication succeeded
Apr 19 16:01:32 phoenix pppd[5970]: CHAP authentication succeeded
Apr 19 16:01:32 phoenix NetworkManager[811]: CHAP authentication succeeded
Apr 19 16:01:32 phoenix NetworkManager[811]: CHAP authentication succeeded
Apr 19 16:01:32 phoenix NetworkManager[811]: nm-pppd-plugin-Message: nm-ppp-plugin: (nm_phasechange): status 8 / phase 'network'
Apr 19 16:01:32 phoenix whoopsie[826]: [16:01:32] Cannot reach: https://daisy.ubuntu.com
Apr 19 16:01:32 phoenix whoopsie[826]: [16:01:32] Cannot reach: https://daisy.ubuntu.com
Apr 19 16:01:35 phoenix pppd[5970]: Could not determine remote IP address: defaulting to 10.64.64.64
Apr 19 16:01:35 phoenix NetworkManager[811]: Could not determine remote IP address: defaulting to 10.64.64.64
Apr 19 16:01:35 phoenix pppd[5970]: local IP address 100.115.3.25
Apr 19 16:01:35 phoenix pppd[5970]: remote IP address 10.64.64.64
Apr 19 16:01:35 phoenix pppd[5970]: primary DNS address 59.144.127.117
Apr 19 16:01:35 phoenix pppd[5970]: secondary DNS address 202.56.215.41
Apr 19 16:01:35 phoenix NetworkManager[811]: local IP address 100.115.3.25
Apr 19 16:01:35 phoenix NetworkManager[811]: remote IP address 10.64.64.64
Apr 19 16:01:35 phoenix NetworkManager[811]: primary DNS address 59.144.127.117
Apr 19 16:01:35 phoenix NetworkManager[811]: secondary DNS address 202.56.215.41
Apr 19 16:01:35 phoenix NetworkManager[811]: nm-pppd-plugin-Message: nm-ppp-plugin: (nm_phasechange): status 9 / phase 'running'
Apr 19 16:01:35 phoenix NetworkManager[811]: nm-pppd-plugin-Message: nm-ppp-plugin: (nm_ip_up): ip-up event
Apr 19 16:01:35 phoenix NetworkManager[811]: nm-pppd-plugin-Message: nm-ppp-plugin: (nm_ip_up): sending IPv4 config to NetworkManager...
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> keyfile: add connection in-memory (d3804110-9c70-456c-ac9b-7f760b90f34a,"ppp0")
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> (ppp0): device state change: unmanaged -> unavailable (reason 'connection-assumed') [10 20 41]
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> (ppp0): device state change: unavailable -> disconnected (reason 'connection-assumed') [20 30 41]
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> Device 'ppp0' has no connection; scheduling activate_check in 0 seconds.
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> (ppp0): Activation: starting connection 'ppp0' (d3804110-9c70-456c-ac9b-7f760b90f34a)
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> PPP manager (IPv4 Config Get) reply received.
Apr 19 16:01:35 phoenix whoopsie[826]: [16:01:35] Cannot reach: https://daisy.ubuntu.com
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> (ppp0): device state change: disconnected -> prepare (reason 'none') [30 40 0]
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> (ttyUSB0): device state change: ip-config -> ip-check (reason 'none') [70 80 0]
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> (ppp0): device state change: prepare -> config (reason 'none') [40 50 0]
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> (ppp0): device state change: config -> ip-config (reason 'none') [50 70 0]
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> (ttyUSB0): device state change: ip-check -> secondaries (reason 'none') [80 90 0]
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> (ppp0): device state change: ip-config -> ip-check (reason 'none') [70 80 0]
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> (ttyUSB0): device state change: secondaries -> activated (reason 'none') [90 100 0]
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> NetworkManager state is now CONNECTED_LOCAL
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> NetworkManager state is now CONNECTED_GLOBAL
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> Policy set 'Airtel Default' (ppp0) as default for IPv4 routing and DNS.
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> Writing DNS information to /sbin/resolvconf
Apr 19 16:01:35 phoenix dnsmasq[1477]: setting upstream servers from DBus
Apr 19 16:01:35 phoenix dnsmasq[1477]: using nameserver 59.144.127.117#53
Apr 19 16:01:35 phoenix dnsmasq[1477]: using nameserver 202.56.215.41#53
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> (ttyUSB0): Activation: successful, device activated.
Apr 19 16:01:35 phoenix nm-dispatcher: Dispatching action 'up' for ppp0
Apr 19 16:01:35 phoenix NetworkManager[811]: <info> (ppp0): device state change: ip-check -> secondaries (reason 'none') [80 90 0]
Apr 19 16:01:35 phoenix whoopsie[826]: [16:01:35] The default IPv4 route is: /org/freedesktop/NetworkManager/ActiveConnection/24
Apr 19 16:01:35 phoenix whoopsie[826]: [16:01:35] Network connection may be a paid data plan: /org/freedesktop/NetworkManager/Devices/16
在第 7 行，我可以看到CHAP authentication succeeded，但我不明白这里还有什么错误。当我执行简单的 时ping google.com，我收到未知主机错误，并且系统日志中打印了以下几行：
Apr 19 16:02:02 phoenix pppd[5970]: IPV6CP: timeout sending Config-Requests
Apr 19 16:02:02 phoenix NetworkManager[811]: IPV6CP: timeout sending Config-Requests
任何指点都会有帮助。
编辑
到目前为止，我发现的唯一解决方法是重新安装network-manager。当我重新安装此软件包然后重新连接时，我就能神奇地连接到互联网了！但我正在寻找一个合适的解决方案，而不是解决方法。
编辑2
看起来像错误报告已经有人在 Launchpad 上提交了此问题。我忘了在问题中提到它，但当我尝试编辑有问题的移动宽带连接时，我也收到以下错误对话框：
settings/nm-settings-connection.c.995 - Connection didn't have requested setting 'ppp'
编辑3
另一个观察结果是，这个错误似乎只发生在华为调制解调器的特定型号上。例如，它发生在我的 Airtel 加密狗上，但在我使用 BSNL 加密狗时不会发生。我还认为这与接口命名有关。对于 Airtel，连接接口被命名为 ，ppp0而对于 BSNL，它被命名为wwt692d89159469，因此这可能对故障排除有用。
答案1
我尝试在互联网上几乎所有地方寻找解决方案，包括这个网站，ubuntuforums.org和launchpad.net。
完成所有这些后，我在此得出结论：（截至 2016-05-29） 中没有修复此问题的方法15.10。解决此问题的唯一方法是升级到16.10。事实上，考虑到过去发生过类似的事情，我一开始就不应该尝试非 LTS 版本！