Network unavailable when resume from suspend after updating Ubuntu 20.04.1

Question

After a recent update of Ubuntu 20.04.1 LTS when I resume my laptop from suspend my WIFI does not work. WIFI does work after rebooting the laptop.

Here is what I have tried.

sudo systemctl restart NetworkManager

sudo service network-manager restart

sudo nmcli networking off

sudo nmcli networking on

Non of these worked. There were no problems before the update and restoring to a previous state with timeshift resolves the problem. Here are the outputs of some commands that my help.

sudo lshw -C network

-network DISABLED

   description: Wireless interface
   product: Centrino Advanced-N 6235
   vendor: Intel Corporation
   physical id: 0
   bus info: pci@0000:02:00.0
   logical name: wlp2s0
   version: 24
   serial: c4:85:08:43:dc:6c
   width: 64 bits
   clock: 33MHz
   capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
   configuration: broadcast=yes driver=iwlwifi driverversion=5.8.0-34-generic firmware=18.168.6.1 6000g2b-6.ucode latency=0 link=no multicast=yes wireless=IEEE 802.11
   resources: irq:31 memory:f1500000-f1501fff

-network

   description: Ethernet interface
   product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
   vendor: Realtek Semiconductor Co., Ltd.
   physical id: 0
   bus info: pci@0000:03:00.0
   logical name: enp3s0
   version: 06
   serial: e8:03:9a:e8:1a:51
   capacity: 1Gbit/s
   width: 64 bits
   clock: 33MHz
   capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
   configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=5.8.0-34-generic firmware=rtl8168e-3_0.0.4 03/27/12 latency=0 link=no multicast=yes port=MII
   resources: irq:19 ioport:2000(size=256) memory:f1404000-f1404fff memory:f1400000-f1403fff

nmcli device

DEVICE TYPE STATE CONNECTION

30:D9:D9:28:09:E4 bt disconnected --

enp3s0 ethernet unavailable --

wlp2s0 wifi unavailable --

lo loopback unmanaged --

lspci -knn | grep Net -A3; rfkill list

02:00.0 Network controller [0280]: Intel Corporation Centrino Advanced-N 6235 [8086:088e] (rev 24)

Subsystem: Intel Corporation Centrino Advanced-N 6235 AGN [8086:4060]
Kernel driver in use: iwlwifi
Kernel modules: iwlwifi

0: phy0: Wireless LAN

Soft blocked: no
Hard blocked: no

2: hci0: Bluetooth

Soft blocked: no
Hard blocked: no

rfkill

ID TYPE DEVICE SOFT HARD

0 wlan phy0 unblocked unblocked

2 bluetooth hci0 unblocked unblocked

EDIT: the problem occur with Linux kernel 5.8 but no with Linux kernel 5.4

Answer 1

Sounds to me like the first thing you should check is if your wireless interface is going into powersave mode maybe? So maybe first try to configure powermanagement referencing this KBA: https://help.ubuntu.com/stable/ubuntu-help/power.html.en if you hadn't done so before.

Wireless powersaving can be changed like this:

Create a file in /etc/pm/config.d named blacklist

gksu gedit /etc/pm/config.d/blacklist

and inside the file keep:

HOOK_BLACKLIST="wireless"

If you want to disable any other hooks, default hooks are located at /usr/lib/pm-utils/power.d/.

Per this KBA:How can I prevent iwconfig power management from being turned on?

It has some alternative ways to achieve the same thing in this post.

Hope that fixes it for you. you might have to reboot after these changes.