WiFi won't activate on stretch

I have an HP laptop running debian stretch, 64bit, installed from netinstall cd.
I added the non-free branch to apt, and installed firmware-iwlwifi like my card needs, but every time I try ifconfig wlp2s0 up, I'm told "SIOCSIFFLAGS: Input/output error"
What further information could I provide that would help remedy this?

What is the wireless chipset?

The command lspci run in a terminal should provide that information.

Intel centrino wireless-n 1000 [condor peak]

Try using ip / iw (modern way).

$ ip link show

# ip link set wlp2s0 up
# wpa_passphrase ESSID PASSWORD > wpa.conf
# wpa_supplicant -Dnl80211,wext -iwlp2s0 -cwpa.conf &
# dhclient -4 -v wlp2s0

Or use a manager like NetworkManager (probably in the way if already installed). Or WICD, depending on your distro / environment.

# nmtui

ip link wlp2s0 up gives me

RTNETLINK answers: Input/output error

Also, I'm using Network Manager; it shows that wifi is on but no networks are showing up at all

# systemctl stop NetworkManager
# pkill wpa_supplicant

How I normally start my day. When your driver is flakey, no manager is going to play nice with that. With it barking I/O "error", it's probably flakey. And with NetworkManager running you cannot modprobe -r the module as it's "in use". Although flakey probably just means missing (or old / wrong version of) firmware.

# ip link set wlp2s0 up
# iw dev wlp2s0 scan
# iwlist wlp2s0 scanning

Although I made a bash script to scape the output of iwlist to put relevant connection information on a single line per SSID found. With the quality/strength as the first part of the output so I could sort -r to know what's closest / best. With encryption on/off status as the last part so I know what's open/free.

Looks like it uses the iwlwifi driver.

https://www.intel.com/content/www/us...etworking.html

Probably with some firmware. Seems to have had a driver since the 2.6.30 kernel. Should work (if only in theory).

https://wireless.wiki.kernel.org/en/...-39.31.5.1.tgz

Another source for the tarball with "schtuff".

$ cp iwlwifi-1000-5.ucode /lib/firmware

From the README in the tarball. Seems to have some strange licensing so probably not included by default in a few (if not all) distros. No firmware generally means no "functional" driver. At least they provide you the firmware. In debian the firmware seems to have that firmware in the package "firmware-iwlwifi".

$ sudo apt-get install firmware-iwlwifi

Which requires the non-free repositories to be enabled. You could check dmesg for any messages saying that it cannot find firmware. Or what version of it it did find.

$ sudo dmesg | grep -i firmware | grep -i iwl

I did install firmware-iwlwifi already. Before I’d installed it, the system complained about not finding iwlwifi as it booted but now the only problem is when trying to activate it

You might install the one from the tarball. It "might" differ from the one supplied by the distro. Doubt it given the age of the driver/firmware. But possible, I got an hp stream 11 in Nov 2014, and the firmware from July 2015 solved a lot of headaches.

You might actually try finding an OLDER version of the firmware. I'm not 100% certain intel still includes firmware for that chipset.

Look if you have the file iwlwifi-1000-ucode* in your firmware.

Also, no idea if this is still pertinent, but in a google, I found someone had to do this to get it to work:

echo "options iwlwifi 11n_disable=1 wd_disable=1" | sudo tee /etc/modprobe.d/iwlwifi.conf
sudo modprobe -rfv iwlwifi
sudo modprobe -v iwlwifi

Back in 2015, someone cleaned oput the kernel's firmware on the basis that 'nobody uses that old sh** anymore.' But LOADS of people use it. Many packages package the older firmware. Slackware does a kernel-firmware package with firmware for the 'old sh**' that installs with a 'tar -xf' from /, and others have their own methods.

Check your system logs and see what it says about firmware. Also try and find where your distro keeps old firmware.