Network-manager randomly won't recognize wireless card after resuming from sleep or hibernation or when disabling/reenabling the card

[Andre Brait]

When resuming from sleep or coming out of hibernation and sometimes when disabing and reenabling the wireless card (using Fn + the corresponding key), network-manager will stop recognizing that there's a wireless card in my laptop. The bluetooth applet and the card themselves still work. I can still connect to the same network it was connected before putting it to sleep/hibernate (because it's a known network and it does so automatically) but network-manager won't display anything regarding me having a wireless card, displaying the icon and information I would expect if I were connected using an ethernet cable.

A workaround consists in restarting the network-manager service using systemctl

sudo service network-manager restart

or

sudo systemctl restart network-manager.service

The system is a Dell Vostro 5470 running a fresh installation of Ubuntu 16.04.1. If I recall correctly, this also happened with Ubuntu 14.04.4 too. BIOS version is A12 (the latest).

I've seen several people with problems like this one that were solved by restarting network-manager (a quick Googling shows a handful of such cases). This can be a huge turn off for a newcomer.

Some people also suggested creating a systemd service to restart the network-manager service when resuming, etc. but since this bug also occurs when disabling/reenabling the card, it might have another cause that's unrelated to resuming from sleep.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: network-manager 1.2.0-0ubuntu0.16.04.3
ProcVersionSignature: Ubuntu 4.4.0-36.55-generic 4.4.16
Uname: Linux 4.4.0-36-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CurrentDesktop: Unity
Date: Fri Sep 16 01:26:01 2016
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
InstallationDate: Installed on 2016-09-10 (6 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
IpRoute:
 default via 192.168.1.1 dev wlp8s0 proto static metric 600
 169.254.0.0/16 dev wlp8s0 scope link metric 1000
 192.168.1.0/24 dev wlp8s0 proto kernel scope link src 192.168.1.248 metric 600
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
ProcEnviron:
 LANGUAGE=pt_BR:pt:en
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=pt_BR.UTF-8
 SHELL=/bin/bash
SourcePackage: network-manager
UpgradeStatus: No upgrade log present (probably fresh install)
nmcli-dev:
 DEVICE TYPE STATE DBUS-PATH CONNECTION CON-UUID CON-PATH
 wlp8s0 wifi connected /org/freedesktop/NetworkManager/Devices/0 That's no moon! 1 2a59043a-02a4-4da0-ab5c-3c89c52bd15f /org/freedesktop/NetworkManager/ActiveConnection/1
 enp7s0 ethernet unavailable /org/freedesktop/NetworkManager/Devices/1 -- -- --
 lo loopback unmanaged /org/freedesktop/NetworkManager/Devices/2 -- -- --
nmcli-nm:
 RUNNING VERSION STATE STARTUP CONNECTIVITY NETWORKING WIFI-HW WIFI WWAN-HW WWAN
 running 1.2.0 connected started full enabled enabled enabled enabled enabled

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.