This is my story with an Intel Dual Band Wireless-AC 3168 (M.2 2230) and Ubuntu Linux:
- I decide to manually update Ubuntu 16.04 LTS, including the kernel/dist-upgrade thing.
- No WiFi connection,
iwconfigcommand returns no adapters.
- While testing several reboots, I notice the wireless adapter sometimes appears and works.
- I decide to install Ubuntu 18.04 LTS from scratch in another hard drive.
- Boot live USB image (18.04.0 Desktop), go to desktop.
- I try Internet connection, I notice WiFi is very slow, like ancient times.
- I plug Ethernet cable and perform a minimal Ubuntu installation with last downloaded updates.
- Reboot, unplug Ethernet cable.
- I try Internet connection, WiFi is very slow.
- I search for solutions, I disable 802.11n (iwlwifi 11n_disable=1), WiFi works (connection speed is lower than 11Mbps), even after reboots.
- Not satisfied with solution, I decide to ask here and run Ubuntu forums network script.
- Network script result is HERE.
Related question threads I found: