Fixing Lost WiFi After Installing a New Kernel on Ubuntu 14.04.2 on the X250

The X250 is a bit of a pain on Ubuntu 14.04 — the touchpad doesn’t work right. Besides the mode tweak I mentioned before, the other fix is upgrading to a newer kernel.

Kernels are everywhere; you can just grab one from Ubuntu’s Mainline and install it, like the latest 4.0.2:

http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.0.2-wily/

But after installing, you’ll find the touchpad works fine and the WiFi is gone. So here is a fix.

Basically, add the driver back manually.

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

My wireless card is an Intel Wireless 7265, so download the 7265 driver from that page.

After extracting you get a pile of files with the .ucode extension. Just copy them into the system directory.

sudo cp *.ucode /lib/firmware/

Reboot and the problem’s gone.