Usb tethering not working in Kubuntu 14.04.5

[Guest]

Hi,
i have recently installed Kubuntu 16.04 and everything worked fine, but i couldn't install AMD drivers so, today, i decided to install Kubuntu 14.04.5. I connect the USB cable and enabled tethering on my android phone but nothing happened. I tried to put interface up and to assign an IP address with dhclient, but it didn't help.

[Guest]

The issue descrived above can be solved by using Linux kernel version 4.4. Anyway, proprietary AMD driver fail to install properly causing the kubuntu-desktop metapackage to be removed by apt. I gave up and switched to Kubuntu 16.04. No issue with Xenial Xerus, beside the fact that i'm forced to use the low quality open source driver.