WiFi network connection unstable after upgrading from 12.04 to 14.04

[Héctor Velarde]

After upgrading from 12.04 to 14.04 on a Dell Vostro 3400 the Wi-Fi network connection became unstable: no automatic connection on start up and no network at all after resuming from an hibernation. Both of them were working previously.

This reports relates to #1340729.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: network-manager 0.9.8.8-0ubuntu7
ProcVersionSignature: Ubuntu 3.13.0-30.55-generic 3.13.11.2
Uname: Linux 3.13.0-30-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.14.1-0ubuntu3.2
Architecture: amd64
Date: Fri Jul 11 09:45:25 2014
ExecutablePath: /usr/sbin/NetworkManager
IfupdownConfig:
 auto lo
 iface lo inet loopback
InstallationDate: Installed on 2010-09-25 (1385 days ago)
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Beta amd64 (20100901.1)
IpRoute:
 default via 10.161.1.5 dev tun0 proto static
 10.161.1.1 via 10.161.1.5 dev tun0 proto static
 10.161.1.5 dev tun0 proto kernel scope link src 10.161.1.6
 192.168.0.0/24 dev wlan0 proto kernel scope link src 192.168.0.15 metric 9
 209.222.15.230 via 192.168.0.1 dev wlan0 proto static
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=false
ProcEnviron:
 LANGUAGE=pt_BR:es_MX:en
 TERM=linux
 PATH=(custom, no user)
 LANG=pt_BR.UTF-8
SourcePackage: network-manager
UpgradeStatus: Upgraded to trusty on 2014-07-07 (3 days ago)
nmcli-dev:
 DEVICE TYPE STATE DBUS-PATH
 eth0 802-3-ethernet unavailable /org/freedesktop/NetworkManager/Devices/1
 wlan0 802-11-wireless connected /org/freedesktop/NetworkManager/Devices/0
nmcli-nm:
 RUNNING VERSION STATE NET-ENABLED WIFI-HARDWARE WIFI WWAN-HARDWARE WWAN
 running 0.9.8.8 connected enabled enabled enabled enabled disabled