How to setup a local-only (offline) Wi-Fi AP with Debian/Raspbian?

##Edit## Error from hostapd: Failed to initialize interface WiFi adapter: Qualcomm Atheros QCA9377 802.11ac Wireless Network Adapter (rev 31) Supported interface modes: * IBSS * managed * AP * monitor * mesh point * P2P-client * P2P-GO * P2P-device valid interface combinations: * #{ managed } = 2, #{ AP, mesh point, P2P-client, P2P-GO } = 2, #{ P2P-device } = 1, total = 4, #channels = 1 * #{ managed } = 2, #{ P2P-client } = 2, #{ AP, mesh point, P2P-GO } = 1, #{ P2P-device } = 1, total = 4, #channels = 2 * #{ managed } = 1, #{ IBSS } = 1, total = 2, #channels = 1 ##Edit## I wish to have a stan

Question by AlonBR on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.