Editing Dell Precision 5520 (section)

=== How to fix immediately: ===
In a terminal, run <code>sudo dmesg | grep -e iwl</code>.

Source (adapted from): https://old.reddit.com/r/kde/comments/ax89sf/wifi_connection_problems_kde_plasma/ehrrmva/

If you get an output similar to the following (there should be an <code>error -110</code> and it should say "<code>probe of (some number) failed</code>"):
 [ 4.409255] iwlwifi 0000:02:00.0: enabling device (0000 -> 0002) 
 [ 5.273078] iwlwifi: probe of 0000:02:00.0 failed with error -110
Then the fix is:

* Force shutdown (hold power button for more than 5 seconds).
* Then reboot into Linux again; WiFi should work.

Source: https://old.reddit.com/r/pop_os/comments/l2ykc2/no_wifi_adapter_found_intel/gk9bg7s/

==== Why it works: ====
Grepping for <code>iwl</code> gets all the kernel messages specific to the Intel wifi driver.

The <code>0000:02:00.0</code> (random numbers) is the PCI device ID of the Intel wifi card. Technically, these numbers are not random, but I simplified it for the purposes of the tutorial. Really, it describes which bus (and the domain number, which is just a group of 256 PCI buses, among other things) the WiFi card is connected to on the motherboard, which maps to the Linux kernel. The Linux kernel decodes PCI data going into it by assigning it these numbers. https://prefetch.net/articles/linuxpci.html

The reason you get error <code>-110</code> is usually because of a common issue with the computer's "hybrid shutdown" mode. The BIOS will preserve the "state" of the WiFi card presumably to make it faster to reboot. Linux unfortunately isn't able to recognize this "state".