The cursed "Intel Wi-Fi 6 AX200 "

So this are my notes on the cursed wifi adapter "Intel Wi-Fi 6 AX200 ".  It has the interesting tendency  to disappear and then you have to reboot for it to reappear. But sometimes it will again disappear just minutes after restart. So a really really naughty adapter. I spent a lot of time searching for a solution, here is what I found.

 The errors:

Error sending STATISTICS_CMD: time out after 2000ms.
[23658.567163] iwlwifi 0000:03:00.0: Current CMD queue read_ptr 56 write_ptr 57

or 

Direct firmware load for iwlwifi ucode failed with error -2

or 

iwlwifi 0000:03:00.0: Error, can not clear persistence bit

There are two parts of the problem that I detected so far.

1) Power management for optimus-manager. That's a tricky one because it appears if it's not configured correctly, at some point the wifi adapter shuts down. 

So this is my config file:

$cat /etc/optimus-manager/optimus-manager.conf
[amd]
dynamic_power_management=fine
DRI=3
driver=modesetting
tearfree=

[intel]
dynamic_power_management=fine
DRI=3
accel=
driver=modesetting
modeset=yes
tearfree=

[nvidia]
dynamic_power_management=fine
DPI=96
PAT=yes
allow_external_gpus=no
ignore_abi=no
modeset=yes
options=overclocking

[optimus]
dynamic_power_management=fine
auto_logout=yes
pci_power_control=no
pci_remove=no
pci_reset=no
startup_auto_battery_mode=integrated
startup_auto_extpower_mode=hybrid #nvidia
startup_mode=hybrid #nvidia
switching=none

2) The more important problem appears to be the wifi firmware. For unknown to humanity reasons, the kernel doesn't install the correct firmware but 20 others. This page expains how to reinstall it.

So  first see the exact adapter you have, unless you haven't.  In Manjaro:

$inxi -N

or 

$lshw -c net 

Then you can check the firmware version with:

$modinfo iwlwifi|grep 7260

Download the wifi driver from the official Intel website.  Extract it somewhere (new_driver). Then:
$ls /usr/lib/firmware | grep -i pnvm
$mv *.pnvm ~/wifi/old
$mv *.ucode ~/wifi/old
$cd new_driver
sudo cp iwlwifi-*.ucode /lib/firmware/

Then reboot.

 3) Aside from this, there is a number of other things to do to try to improve the life of your adapter. I'm listing them below, I don't know which help and which don't I just did everything.

$sudo iw reg set BG #where BG is the code of YOUR country
$sudo nano /etc/modprobe.d/iwlwifi.conf
>
options iwlwifi 11n_disable=1
options iwlwifi 11n_disable=8
optwion iwlwifi wd_disable=1
ctrl+o
$sudo iw wlan0 set power_save off #this didn't work for me
$sudo iw wlp3s0 set power_save off
$sudo nano /etc/modprobe.d/wifi.conf 

> 

options iwlmvm power_scheme=1
options iwlwifi swcrypto=0 bt_coex_active=0 power_save=0 11n_disable=1 

ctrl+o

$sudo nano /etc/modprobe.d/iwlmvm.conf: 

>

options iwlmvm power_scheme=1

Key websites if you want to dig in:

https://wireless.wiki.kernel.org/en/users/drivers/iwlwifi

https://itslinuxfoss.com/install-intel-wifi-6-ax200-driver/
https://www.intel.com/content/www/us/en/support/articles/000005511/wireless.html.

Also see this: https://bbs.archlinux.org/viewtopic.php?id=243671

But here after modeprobing the device was not visible in ifconfig and I could not try to "up" it. (also, ifconfig now is " ip a" )

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1848921

https://bbs.archlinux.org/viewtopic.php?id=243671

https://wireless.wiki.kernel.org/en/users/drivers/iwlwifi

https://askubuntu.com/questions/1205996/iwlwifi-causing-system-hangs-on-ubuntu-19-10

https://launchpad.net/ubuntu/+source/linux-firmware/1.143.1

https://askubuntu.com/questions/616119/unstable-wireless-with-intel-7260-iwlwifi-after-upgrade-to-15-04