I use Ubuntu14 OS and build https://wireless.wiki.kernel.org/en/users/drivers/iwlwifi/core_release iwlwifi module(core24). I use it as a client very well and also use hostapd program create AP mode with 802.11n(2.4G) std. However, I can not setup 802.11ac(5G) mode one? How can we do?
We would like to inform that the Intel® Wireless Adapters and drivers support basic Ad-hoc functionality, however, they are not meant to be used as Hotspot. We understand you may be able to achieve this with 3rd party software, however, this would be out of the scope of support for the adapter.
In this case, we advise you to check external forums of the software you are using, or for you Linux distribution, as you may be able to find more information from other users.