I have and AMD X570 mobo, AMD 5600X CPU, an installed Intel Wi-Fi 6 AX200 (Gig+) m.2 wireless card, and the KDE neon-user-20210211-0944 distribution. Kernel is 5.4.0-65-generic. Wired ethernet works, and the wireless card also works on Win10, but wireless does not work on linux/neon.

I did:

% sudo apt install backport-iwlwifi-dkms
... and...
% git clone https://git.kernel.org/pub/scm/linux/ke ... wlwifi.git
.... and put the .ucode files in /lib/firmware

I'm no expert on this stuff, but the outputs below make me suspect that the driver/module is looking for a firmware version that I don't have (and cannot find), see below:

% sudo lshw -C network
*-network
description: Ethernet interface
product: I211 Gigabit Network Connection
vendor: Intel Corporation
..........
configuration: autonegotiation=on broadcast=yes driver=igb driverversion=5.6.0-k duplex=full firmware=0. 4-1 ip=192.168.1.18 latency=0 link=yes multicast=yes port=twisted pair speed=1Gbit/s
resources: irq:37 memory:fc600000-fc61ffff ioport:f000(size=32) memory:fc620000-fc623ff

% sudo lspci -nnk | grep -i intel
05:00.0 Ethernet controller [0200]: Intel Corporation I211 Gigabit Network Connection [8086:1539] (rev 03)
Kernel driver in use: snd_hda_intel
Kernel modules: snd_hda_intel
Kernel driver in use: snd_hda_intel
Kernel modules: snd_hda_intel

(ie. wired interface is present *but not* wireless)

% modinfo iwlwifi | grep iwlwifi-cc
firmware: iwlwifi-cc-a0-63.ucode

% ls /lib/firmware | grep iwlwifi-cc
iwlwifi-cc-a0-46.ucode
iwlwifi-cc-a0-48.ucode
iwlwifi-cc-a0-50.ucode
iwlwifi-cc-a0-53.ucode
iwlwifi-cc-a0-55.ucode
iwlwifi-cc-a0-59.ucode

(iwlwifi-cc microcode is in /lib/firmware as versions up to 59, but not version 63)

% journalctl | grep iwl

Feb 15 07:38:48 Jboat18 kernel: Loading modules backported from iwlwifi
Feb 15 07:38:48 Jboat18 kernel: iwlwifi-stack-public:master:9022:a34beadd
Feb 15 07:38:48 Jboat18 systemd-modules-load[433]: Inserted module 'iwlwifi'

% lsmod | grep iwl
iwlwifi 389120 0
cfg80211 712704 1 iwlwifi
compat 16384 2 iwlwifi,cfg80211

After working on my iwlwifi problem for days, the solution below worked for me. Context .... while my system is now running linux KDE Neon, it had previously run Windows 10, and AX200 wifi worked on that. After installing linux, I created a bootable "Win2go" USB flash drive, and booted off that several times just to make sure the AX200 was still working. I never cease to be amazed at how Windows can screw up a system.

Error message on linux:
iwlwifi: probe of XXXX:YY:ZZ.n failed with error -110

Solution:
https://askubuntu.com/questions/1083369 ... ss-ac-9260

.....................
"It is a problem with fast startup mode of Windows. I think because in that mode, Windows keeps the wireless adapter for itself when shut down. hence Linux cannot detect it.

Just go into Settings > Power & Sleep > Choose what power button does > Shut down setting > uncheck the Turn on fast startup > save change and it will work."

It might be a good idea for Intel to put this in their linux Wifi Troubleshooting guide.