Can't I use IEEE 802.11ac on this driver?

[EmmanuelChanel]

I have a linux router. It has 1 WAN port, 1, LAN port, and a USB 3.0 WLAN port with BUFFALO WI-U3-866DS. I use this driver for the WLAN port with hostapd. And now I can use 2.4GHz link I want to use IEEE 802.11ac, 5GHz link. When I put ieee80211ac=1 on /etc/hostapd/hostapd.conf , hostapd doesn't work. Isn't there a way to use IEEE 802.11ac with this driver?