I am having the exact same problem. I have been in all kinds of Power Management settings to try to fix the issue. It appears ASUS has the Wi-Fi set to time out with the Power Save mode. You have to go into your power management settings then advanced settings (blue hyperlink) towards the bottom. Look for Network Adapters and WiFi. Then select Maximum Performance instead of Power save Mode or something like that. I noticed that when I would restart the laptop the Wi-Fi would turn back on. So I assumed the laptop was set to make the Wi-Fi hibernate somehow. I just want it on 24 hours.
I tried the other suggestions found online also. Like going into Device Manager selecting network adapters uninstalling the one for Wi-Fi then refreshing and allowing the laptop to reinstall the driver automatically. That worked for the first time only.
I then went into Control Panel and Network and Sharing center. Then going into advanced settings for the Wi-Fi and then selecting the configure button. Then power management tab, and unchecking the radio box, that said "allow this PC to turn off Wi-Fi when saving on battery life." or something like that. I unchecked that box as well. That also didn't do anything.
I am so sick of this problem. Its just this ASUS laptop having this problem. My LG smartTV, Samsung Galaxy 7 Phone, HP wireless printer, and other devices all stay connected to the Wi-Fi. It's only the ASUS Laptop that wont stay connected until you restart it! Their website wont even help you find a solution.