[Bug 1931301] Re: NIC unavailable after suspend to RAM

> Trying to ifconfig it down/up results in:
> SIOCSIFFLAGS: No such device

that likely means the kernel driver had some problem waking the device
back up, but there's no dmesg attached to the bug so i don't know. This
is probably a bug in the 'alx' kernel driver (or, problem with the
hardware), not network-manager.

** Package changed: network-manager (Ubuntu) => linux (Ubuntu)

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https://bugs.launchpad.net/bugs/1931301

Title:
NIC unavailable after suspend to RAM

Status in linux package in Ubuntu:
Confirmed

Bug description:
Upgraded to 21.04 (hirsute) and now the network card is unavailable
after suspend to RAM (sleep state S3). It worked flawlessly up until
20.10. My workaround for now is unloading and reloading the kernel
module, but that won't work for normal users, hence this report.

NIC in its unavailable state:
2: enp4s0: <BROADCAST,MULTICAST> mtu 1500 qdisc mq state DOWN group default qlen 1000
link/ether d0:50:99:27:02:11 brd ff:ff:ff:ff:ff:ff

NIC (from lspci):
04:00.0 Ethernet controller: Qualcomm Atheros Killer E220x Gigabit Ethernet Controller (rev 10)

Trying to ifconfig it down/up results in:
SIOCSIFFLAGS: No such device

journalctl shows (right after recovering from suspend):
NetworkManager[1911]: <info> [1623181236.9371] manager: sleep: wake requested (sleeping: yes enabled: yes)
NetworkManager[1911]: <info> [1623181236.9372] device (enp4s0): state change: unmanaged -> unavailable (reason 'managed', sys-iface-state: 'external')
NetworkManager[1911]: <info> [1623181236.9382] manager: NetworkManager state is now CONNECTED_LOCAL

ProblemType: Bug
DistroRelease: Ubuntu 21.04
Package: network-manager 1.30.0-1ubuntu3
ProcVersionSignature: Ubuntu 5.11.0-18.19-generic 5.11.17
Uname: Linux 5.11.0-18-generic x86_64
ApportVersion: 2.20.11-0ubuntu65.1
Architecture: amd64
CasperMD5CheckResult: unknown
Date: Tue Jun 8 21:59:15 2021
IfupdownConfig:
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback
InstallationDate: Installed on 2016-08-25 (1748 days ago)
InstallationMedia: Ubuntu-MATE 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
RfKill:

SourcePackage: network-manager
UpgradeStatus: Upgraded to hirsute on 2021-06-04 (4 days ago)
nmcli-nm:
RUNNING VERSION STATE STARTUP CONNECTIVITY NETWORKING WIFI-HW WIFI WWAN-HW WWAN
running 1.30.0 connected started full enabled enabled enabled enabled enabled

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