Networking occasionally doesn't recover from suspend

[Phill]

Occasionally, networking is disabled upon recovery from suspend. Clicking "Enable Networking" on the menu from the notification icon has no effect. It requires network-manager to be restarted with `service network-manager restart`.

I can't identify a pattern to the problem. I can suspend the computer for minutes or hours without it happening.

I've not noticed it on other computers running 14.04 that I have, so it's probably limited to my this particular hardware.

I didn't notice it on previous versions of Ubuntu on this hardware. However, due to the nature of the problem it will not be practical to bisect the kernel as I don't have a reliable method of reproducing the fault as of yet.

My network devices are as follows (I use the wireless one only):

Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 02)
Network controller: Qualcomm Atheros AR9287 Wireless Network Adapter (PCI-Express) (rev 01)

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: network-manager 0.9.8.8-0ubuntu7.1
ProcVersionSignature: Ubuntu 3.16.0-48.64~14.04.1-generic 3.16.7-ckt15
Uname: Linux 3.16.0-48-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.12
Architecture: amd64
CurrentDesktop: Unity
Date: Sat Sep 12 12:44:30 2015
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
InstallationDate: Installed on 2015-07-13 (60 days ago)
InstallationMedia: Ubuntu 14.04.2 LTS "Trusty Tahr" - Release amd64 (20150218.1)
IpRoute:
 default via 192.168.1.1 dev wlan1 proto static
 192.168.1.0/24 dev wlan1 proto kernel scope link src 192.168.1.2 metric 9
 192.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
 WimaxEnabled=true
RfKill:
 0: phy0: Wireless LAN
  Soft blocked: no
  Hard blocked: no
SourcePackage: network-manager
UpgradeStatus: No upgrade log present (probably fresh install)
nmcli-con:
 NAME UUID TYPE TIMESTAMP TIMESTAMP-REAL AUTOCONNECT READONLY DBUS-PATH
 HTC Portable Hotspot DF99 b31b75bc-5b76-4592-9b4a-d9d860ea34aa 802-11-wireless 1441832180 Wed 09 Sep 2015 21:56:20 BST yes no /org/freedesktop/NetworkManager/Settings/1
 TALKTALK-D069DC 700ea4cb-a660-479e-aa32-c00ad71e9064 802-11-wireless 1442058263 Sat 12 Sep 2015 12:44:23 BST yes no /org/freedesktop/NetworkManager/Settings/0
nmcli-dev:
 DEVICE TYPE STATE DBUS-PATH
 eth1 802-3-ethernet unavailable /org/freedesktop/NetworkManager/Devices/1
 wlan1 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 enabled

[Phill (phill.l)]

I have also confirmed this problem on a completely different computer, it uses the ath9k driver:

$ lspci
00:00.0 Host bridge: Intel Corporation 4 Series Chipset DRAM Controller (rev 03)
00:02.0 VGA compatible controller: Intel Corporation 4 Series Chipset Integrated Graphics Controller (rev 03)
00:02.1 Display controller: Intel Corporation 4 Series Chipset Integrated Graphics Controller (rev 03)
00:1a.0 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #4
00:1a.1 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #5
00:1a.2 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #6
00:1a.7 USB controller: Intel Corporation 82801JI (ICH10 Family) USB2 EHCI Controller #2
00:1b.0 Audio device: Intel Corporation 82801JI (ICH10 Family) HD Audio Controller
00:1c.0 PCI bridge: Intel Corporation 82801JI (ICH10 Family) PCI Express Root Port 1
00:1d.0 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #1
00:1d.1 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #2
00:1d.2 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #3
00:1d.7 USB controller: Intel Corporation 82801JI (ICH10 Family) USB2 EHCI Controller #1
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 90)
00:1f.0 ISA bridge: Intel Corporation 82801JIR (ICH10R) LPC Interface Controller
00:1f.2 SATA controller: Intel Corporation 82801JI (ICH10 Family) SATA AHCI Controller
00:1f.3 SMBus: Intel Corporation 82801JI (ICH10 Family) SMBus Controller
01:00.0 Network controller: Qualcomm Atheros AR9287 Wireless Network Adapter (PCI-Express) (rev 01)
02:03.0 FireWire (IEEE 1394): LSI Corporation FW322/323 [TrueFire] 1394a Controller (rev 70)

sudo lshw -C network
[sudo] password for phill:
  *-network
       description: Wireless interface
       product: AR9287 Wireless Network Adapter (PCI-Express)
       vendor: Qualcomm Atheros
       physical id: 0
       bus info: pci@0000:01:00.0
       logical name: wlp1s0
       version: 01
       serial: 64:70:02:6e:fe:03
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
       configuration: broadcast=yes driver=ath9k driverversion=4.4.0-22-generic firmware=N/A ip=192.168.43.218 latency=0 link=yes multicast=yes wireless=IEEE 802.11bgn
       resources: irq:16 memory:feaf0000-feafffff

[Phill (phill.l)]

Not a duplicate of #1380480 as that bug report clearly states that disabling and enabling networking in the applet restores the network. This bug report clearly states that has been tried and does not work.

Note that since 16.04 I've been getting this on all computers that I have and a lot more frequently. A separate bug has been raised for that as it was a different operating system and affects different hardware. See #1589125.