I have recently installed 18.04 on a friends' brand new laptop. Everything worked flawlessly. The laptop could connect to all access points we tried. Except for one... There is one particular access point (the access point the ISP's modem provides) that it does not want to connect to. The wifi status stays on "connecting" for almost a minute, and then asks for the password again. This password has been checked multiple times, but is definitely correct. All other devices in the house (including a different laptop with Ubuntu 18.04) can connect just fine with this network that hasn't been altered in years.
I pasted the output of dmesg here (Truncated version, it showed this output multiple times). Not sure what the relevant parts of the dump are, but these lines looked interesting to me:
[12059.864549] iwlwifi 0000:00:14.3: Failed to send binding (action:3): -5 [12059.864552] iwlwifi 0000:00:14.3: Failed to send MAC context (action:2): -5 [12059.864553] iwlwifi 0000:00:14.3: failed to update MAC c8:09:a8:ee:b1:55 [12059.864556] iwlwifi 0000:00:14.3: PHY ctxt cmd error. ret=-5 [12059.885003] iwlwifi 0000:00:14.3: Applying debug destination EXTERNAL_DRAM [12060.034524] iwlwifi 0000:00:14.3: FW already configured (0) - re-configuring [12069.158052] wlp0s20f3: authenticate with dc:53:7c:34:56:17 [12069.162964] wlp0s20f3: send auth to dc:53:7c:34:56:17 (try 1/3) [12069.222006] wlp0s20f3: authenticated [12069.224063] wlp0s20f3: associate with dc:53:7c:34:56:17 (try 1/3) [12069.238359] wlp0s20f3: RX AssocResp from dc:53:7c:34:56:17 (capab=0x411 status=0 aid=1)
It seems like authentication works just fine, but association fails. Also, there seem to be some hardware/driver issues. Googling this output didn't bring up much relevant results.
I then found Unable to connect to specific wifi network . This question looks identical, but unfortunately the solution didn't work.
Because I suspected a driver problem, I checked the "Additional Drivers" tab in Software & Updates. It showed me Intel Corporation: Unknown device. The options to choose from were greyed out.
After a lot more unsuccessful experimenting, I erased the drive and installed Ubuntu 20.04, in the hopes that this would fix it (Because I read something on a page where they suggested a fix that did not work for me on 18.04, but was supposed to be already included in 20.04). Unfortunately, the problem persisted. This time however, in "Additional Drivers" it showed the model of the wifi-card: AC-9462. Googling this model showed a bunch of Linux users having problems with this card. Including this one: Intel Wireless AC 9462 not working w/ 18.04 LTS . I was very hopeful at this point. I installed the fix (the one from the PPA). It "un-greyed" the options in Additional Drivers, but unfortunately did not fix the connection issue.
Then finally I stumbled on this page: https://bugzilla.kernel.org/show_bug.cgi?id=201319 . Multiple users reported Windows Fast Boot to be the culprit, and disabling it solved the issue for them. It is speculated that Windows alters the device in some way, preventing Linux from using it.
This is also written on the wiki of kernel.org: https://wireless.wiki.kernel.org/en/users/drivers/iwlwifi#about_dual-boot_with_windows_and_fast-boot_enabled
About dual-boot with Windows and "fast-boot" enabled
If you have a dual-boot machine with a recent version of Windows and start seeing problems during initialization of the WiFi device when booting Linux, the problem could be due to the “fast startup” feature on Windows.
With this feature enabled, Windows don't really shut down the entire system, but leaves things partially running so you can start the machine faster again. Try to disable this option, on Windows 10 it should be in “Control Panel→Hardware and Sound→Power Options→System Settings”, then disable the “Fast Startup” option in “Shutdown Settings”. This will cause Windows to fully shutdown and may solve the issue.
Even though everyone unanimously agreed that this was the issue, I'm a bit skeptical if this is the issue in my case. Windows was installed on this computer, yes. But it was removed entirely before installing Linux. I don't think remnants of it can cause this issue, can it? In case the answer is "Yes they can!", then how can I fix this? Because Windows has been removed entirely, I can't open the control panel to disable the fast boot option anymore... (I did disable Fast Boot in the BIOS, but this is an entirely different setting if I understand it correctly)
So, after hours of trying and experimenting, I've run out of ideas... Anyone know how I can fix this?
As requested by @chilli555 :
iwlwifi-9000-pu-b0-jf-b0-33.ucode iwlwifi-9000-pu-b0-jf-b0-34.ucode iwlwifi-9000-pu-b0-jf-b0-38.ucode iwlwifi-9000-pu-b0-jf-b0-41.ucode iwlwifi-9000-pu-b0-jf-b0-43.ucode iwlwifi-9000-pu-b0-jf-b0-46.ucode