Wi-Fi disappeared and reappeared the next morning. Why?

Ubuntu 21.10. My laptop battery had fully drained and wouldn’t charge at all with several PD chargers I tried. I dug through forums and followed the advice about plugging a “dumb” (non-PD) charger into one side and a PD charger into the other side, and that did the trick. It started charging.

Then, after booting up, I was able to see the Wi-Fi controller in lspci but it would not show up in the status bar, network manager, iwconfig, or ifconfig. Googled for an hour, found nothing useful. Shut down and went to sleep.

The next morning, I booted up (battery now fully charged) and the Wi-Fi magically came back.

NO software updates throughout this entire process.

Can anyone explain what might have happened? I’d hate to be travelling far away and have my Wi-Fi suddenly fail without notice. Is there something that causes the Wi-Fi controller to fail if the battery is below a certain percentage, or some other known quirk?

I think this might be a kernel issue. What kernel are you running?

I just had the same thing happen with Manjaro. I was traveling. Used my laptop heavily in Grenada last week and on the flight home. Turned on this morning and the system saw the wifi, but wouldn’t connect to any networks. When I turned off bluetooth, wifi entirely disappeared and wouldn’t come back. Rebooted, but the same thing. Interestingly, this happened to me when I returned from Belize a few weeks ago.

I turned on my laptop this evening and everything just worked. Stumped, but too jetlagged to debug it for a few days.

I’m on kernel 5.15.32-1, btw.

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You don’t mention dual booting windows, but it might be worth dropping this here because I’ve had a very similar experience and it seemed as if it was Linux at fault when it was actually to do with Windows fast boot.

Basically Windows doesn’t fully shutdown by default and it was keeping a hold of my wifi controller so Linux couldn’t access it.

You can fully shutdown windows by holding shift when shutting down or I believe you can turn the feature off somehow.

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