Question: I've just upgraded from Ubuntu 14.04 to 15.04 and now my Wifi has ceased to work. I can see the connections, I just cannot connect. This worked perfectly under 14.04. I've read most of the forums and haven't had any luck. Disabling "n" didn't work. I renamed a few files, that didn't work (they have since been set to their original names).

Here's the output from running the wireless-info script:

<http://pastebin.com/VpgSfLq6>

Can anyone offer any assistance?

Answer: 
This issue seems only to apply to the Intel® Wireless 3160.

[This workaround](https://askubuntu.com/a/614584/407698) solved my problem and it seems as though it worked for a few others as well. It basically rolls back the driver to the previous version. While it's not the preferable solution, it works until they patch the kernel.

For those who are much more technically able than I, [here](https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1442411) is the complete bug report including links to the kernel revision that fixes this problem.
I see from your wireless-info output that you have an Intel wireless chipset using the `iwlwifi` driver, which my laptop uses also. I can't determine exactly what is wrong from the information provided, but I can give you some suggestions of things that have worked for me.

**Is this on a laptop which has recently been suspended?** Sometimes after waking up my Thinkpad from being suspended, I can no longer connect to my WPA2-encrypted network. (It looks like you are also using WPA2) I noticed that I could still connect to unencrypted "open" networks, though, which led me to suspect the `wpa_supplicant` process.

It turns out others have had this problem with the `iwlwifi` module after suspending: [Can't connect to WiFi after suspend](https://askubuntu.com/questions/564556/cant-connect-to-wifi-after-suspend/566177#566177)

The key to the fix given in the link above is the line that kills the `wpa_supplicant` process. (It gets restarted automatically, and in my experience that is enough to get it working again) To test if this works for you, run this from a terminal:

```
sudo pkill wpa_supplicant

```

If that fixes things, then you may want to check out the script given in the link above.

If that doesn't help, one other thing to try: **unload and reload `iwldvm` kernel module**.

```
sudo modprobe -r iwldvm && sudo modprobe iwldvm

```

I used to have intermittent wifi problems that would be cleared up by doing the above. I 

Wondering what the difference is between `iwlwifi` and `iwldvm`? I was too, and there's a good explanation here: 
[Is iwlwifi or iwldvm or wext the wireless driver?](https://askubuntu.com/questions/618283/is-iwlwifi-or-iwldvm-or-wext-the-wireless-driver)

Those are two pretty easy things to try.

If those don't work, here's a somewhat more involved approach from someone who has a similar sounding post-upgrade problem with the same `iwlwifi` driver: [Unstable wireless with Intel 7260 + iwlwifi after upgrade to 15.04](https://askubuntu.com/questions/616119/unstable-wireless-with-intel-7260-iwlwifi-after-upgrade-to-15-04)

This involves installing a newer **mainline kernel package** which requires a few steps and may lead to other problems as noted here: [Should I upgrade to the "mainline" kernels?](https://askubuntu.com/questions/162616/should-i-upgrade-to-the-mainline-kernels)

So I would recommend trying the first two simpler fixes first.