I just bought an Asus X552L (network card: 802.11 ac) and installed Ubuntu Gnome 15.04. I can connect to the internet via Wi-Fi. But very often the internet will stop working (Ubuntu still thinks it is connected) and the only thing that will fix it is to either reboot the computer or turn the Wi-Fi off and then on again.
I suspect a problem with the drivers and tried to install the ath10k drivers following the steps mentioned by Jeremy31 (ath10k installation). However after I did this networking would not work at all.
The problem persist with Ubuntu Gnome 14.04 as well.
lspci -knn | grep Net -A2: (as requested by Pilot6)
03:00.0 Network controller : Realtek Semiconductor Co., Ltd. RTL8821AE 802.11ac PCIe Wireless Network Adapter [10ec:8821]
Subsystem: AzureWave Device [1a3b:2161]
Kernel driver in use: rtl8821ae