Network Troubleshooting help, please

[Head_on_a_Stick]

Running Sid 5.9.0-5-amd64 on an LG Gram
After update/upgrade yesterday and without rebooting, my network stopped working
It doesn't appear to be a hardware issue because a Knoppix live CD has network connectivity and dual booting into Windows has network connectivity
Wifi doesn't work, and plugging in a USB ethernet adapter also doesn't give me network connectivity
I have done the following:
Rebooted and have booted in to the previous kernel multiple times

lspci (just showing Network Controller)

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03:00.0 Network controller: Intel Corporation Wireless 8265 / 8275 (rev 78)
   Subsystem: Intel Corporation Wireless 8265 / 8275
   Flags: bus master, fast devsel, latency 0, IRQ 139, IOMMU group 12
   Memory at d1000000 (64-bit, non-prefetchable) [size=8K]
   Capabilities: [c8] Power Management version 3
   Capabilities: [d0] MSI: Enable+ Count=1/1 Maskable- 64bit+
   Capabilities: [40] Express Endpoint, MSI 00
   Capabilities: [100] Advanced Error Reporting
   Capabilities: [140] Device Serial Number f8-63-3f-ff-ff-62-58-59
   Capabilities: [14c] Latency Tolerance Reporting
   Capabilities: [154] L1 PM Substates
   Kernel driver in use: iwlwifi
   Kernel modules: iwlwifi

sudo lshw -C network

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  *-network DISABLED             
       description: Wireless interface
       product: Wireless 8265 / 8275
       vendor: Intel Corporation
       physical id: 0
       bus info: pci@0000:03:00.0
       logical name: wlp3s0
       version: 78
       serial: f8:63:3f:62:58:59
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
       configuration: broadcast=yes driver=iwlwifi driverversion=5.9.0-5-amd64 firmware=36.79ff3ccf.0 8265-36.ucode latency=0 link=no multicast=yes wireless=IEEE 802.11
       resources: irq:139 memory:d1000000-d1001fff

sudo ifup wlp3s0

sudo systemctl restart NetworkManager.service

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  Failed to restart NetworkManager.service: Unit NetworkManager.service is masked.

What can I try next?

[Head_on_a_Stick]

Why have you masked NetworkManager? Which software are you using to connect?

If you don't know then you probably shouldn't be messing around with the development branches but post the output of

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ls -lR /etc/systemd/system/multi-user.target.wants

EDIT: thank you for helping all those cats and dogs, you are awesome.

[Head_on_a_Stick]

Thank you Head_on_a_stick...I wasn't aware that I had masked NetworkManager. Apparently it's a common problem though. As far as my choice of Sid, I'm aware that I'm not much of an expert, but I enjoy learning. I've been using Linux for 20 plus years and the few times I have difficult problems, I'm able to rely on the kindness of strangers such as yourself. Thank you for your help, and thank you for the kind words about my profession.
Larry

Here's the output of the statement:

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sudo ls -lR /etc/systemd/system/multi-user.target.wants
/etc/systemd/system/multi-user.target.wants:
total 0
lrwxrwxrwx 1 root root 35 Jun 21  2019 anacron.service -> /lib/systemd/system/anacron.service
lrwxrwxrwx 1 root root 40 Jun 21  2019 avahi-daemon.service -> /lib/systemd/system/avahi-daemon.service
lrwxrwxrwx 1 root root 42 May 12  2020 binfmt-support.service -> /lib/systemd/system/binfmt-support.service
lrwxrwxrwx 1 root root 41 Jun 21  2019 console-setup.service -> /lib/systemd/system/console-setup.service
lrwxrwxrwx 1 root root 32 Jun 21  2019 cron.service -> /lib/systemd/system/cron.service
lrwxrwxrwx 1 root root 40 Jun 21  2019 cups-browsed.service -> /lib/systemd/system/cups-browsed.service
lrwxrwxrwx 1 root root 29 Jun 21  2019 cups.path -> /lib/systemd/system/cups.path
lrwxrwxrwx 1 root root 37 May 16  2020 duplicati.service -> /lib/systemd/system/duplicati.service
lrwxrwxrwx 1 root root 37 Jun 21  2019 minissdpd.service -> /lib/systemd/system/minissdpd.service
lrwxrwxrwx 1 root root 40 Jun 21  2019 ModemManager.service -> /lib/systemd/system/ModemManager.service
lrwxrwxrwx 1 root root 38 Jun 21  2019 networking.service -> /lib/systemd/system/networking.service
lrwxrwxrwx 1 root root 42 Jun 21  2019 NetworkManager.service -> /lib/systemd/system/NetworkManager.service
lrwxrwxrwx 1 root root 37 Nov 24  2019 nfs-client.target -> /lib/systemd/system/nfs-client.target
lrwxrwxrwx 1 root root 32 Nov 16  2019 nmbd.service -> /lib/systemd/system/nmbd.service
lrwxrwxrwx 1 root root 31 Apr  2  2020 ntp.service -> /lib/systemd/system/ntp.service
lrwxrwxrwx 1 root root 35 Dec 10 07:36 orthanc.service -> /lib/systemd/system/orthanc.service
lrwxrwxrwx 1 root root 34 Mar  1  2020 piavpn.service -> /etc/systemd/system/piavpn.service
lrwxrwxrwx 1 root root 38 Feb 28  2020 postgresql.service -> /lib/systemd/system/postgresql.service
lrwxrwxrwx 1 root root 36 Jun 21  2019 pppd-dns.service -> /lib/systemd/system/pppd-dns.service
lrwxrwxrwx 1 root root 36 Jun 21  2019 remote-fs.target -> /lib/systemd/system/remote-fs.target
lrwxrwxrwx 1 root root 35 Nov 24  2019 rpcbind.service -> /lib/systemd/system/rpcbind.service
lrwxrwxrwx 1 root root 33 Nov 13  2019 rsync.service -> /lib/systemd/system/rsync.service
lrwxrwxrwx 1 root root 35 Jun 21  2019 rsyslog.service -> /lib/systemd/system/rsyslog.service
lrwxrwxrwx 1 root root 32 Nov 16  2019 smbd.service -> /lib/systemd/system/smbd.service
lrwxrwxrwx 1 root root 31 Jun 21  2019 tor.service -> /lib/systemd/system/tor.service
lrwxrwxrwx 1 root root 47 Jun 21  2019 unattended-upgrades.service -> /lib/systemd/system/unattended-upgrades.service
lrwxrwxrwx 1 root root 35 Nov  6  2019 vboxweb.service -> /lib/systemd/system/vboxweb.service
lrwxrwxrwx 1 root root 37 Apr 20  2020 wg-quick@wg0.service -> /lib/systemd/system/wg-quick@.service
lrwxrwxrwx 1 root root 42 Jun 21  2019 wpa_supplicant.service -> /lib/systemd/system/wpa_supplicant.service

[Head_on_a_Stick]

So does unmasking NetworkManager get things working again?

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# systemctl unmask NetworkManager
# systemctl start NetworkManager

I don't think wpa_supplicant should be enabled (NM should start it) so it might be best to also disable that beforehand to avoid potential conflicts:

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# systemctl disable --now wpa_supplicant

EDIT: how did you install that VPN? It might be causing trouble.

[drfox]

Uh oh...I told you that this coincided with my updating and upgrading. I think the upgrade process removed a component of NM. I have had PIA for some years and haven't used it in a long time. I disabled wpa_supplicant and then:

sudo systemctl unmask NetworkManager
Removed /etc/systemd/system/NetworkManager.service.
sudo systemctl start NetworkManager
Failed to restart NetworkManager.service: Unit NetworkManager.service not found.

Rebooting did not fix things, and sudo ls -lR /etc/systemd/system/multi-user.target.wants command still gives me this:
lrwxrwxrwx 1 root root 42 Jun 21 2019 NetworkManager.service -> /lib/systemd/system/NetworkManager.service

Strangely, NM seems to still be present in the system:
/etc/NetworkManager# ls -l
total 16
drwxr-xr-x 2 root root 4096 Apr 8 2020 conf.d
drwxr-xr-x 2 root root 4096 Dec 26 09:16 dispatcher.d
-rw-r--r-- 1 root root 58 Dec 28 08:16 NetworkManager.conf
drwxr-xr-x 2 root root 4096 Dec 23 09:03 system-connections

Is it possible to get a NetworkManager deb and reinstall it? Would that even work, or could I be missing some other requisite component?

[Head_on_a_Stick]

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     Failed to restart NetworkManager.service: Unit NetworkManager.service not found.

That's strange — if /lib/systemd/system/NetworkManager.service was missing then /etc/systemd/system/multi-user.target.wants/NetworkManager.service would be a dangling symlink but it's clearly still present and correct.

Double check:

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stat /lib/systemd/system/NetworkManager.service
dpkg -L network-manager | grep '*.service'
dpkg -S /lib/systemd/system/NetworkManager.service
dpkg --verify network-manager

The unit file is supplied by the network-manager package.

What does systemd itself think?

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systemctl cat NetworkManager.service

Here's the original file: https://salsa.debian.org/utopia-team/ne ... service.in

Is it possible to get a NetworkManager deb and reinstall it?

Yes. Check /var/cache/apt/archives/ to see if you still have the .deb or download it from here (on another machine).

But you don't need NM to connect: https://dev1galaxy.org/viewtopic.php?pid=26326#p26326

[drfox]

Whew! Nothing I needed was in my cache, but your link showed me the logic of downloading what I needed.
Reinstalling NM after getting some dependencies did the trick.
libbluetooth3_5.55-2_amd64.deb
libndp0_1.6-1+b1_amd64.deb
libteamdctl0_1.31-1_amd64.deb
libnm0_1.28.0-1+b1_amd64.deb
Thank you so much for the help. Can I make a donation? BLM or Devuan? Send me a PM with a link.
Happy, healthy 2021
Larry

[Head_on_a_Stick]

Thank you so much for the help.

You're welcome. Glad you got it fixed.

Can I make a donation?

That would be fantastic, thank you. I prefer cat charities but whatever you think is best.

https://www.debian.org/donations