This example is using RTL8821AU chipset from a TP-Link T2U Plus USB adapter and other similar ones should work the same.
Here's how to get this chipset RTL8821AU working in Linux.
Here's how to get RTL8812 and RTL8822 working in Linux.........
Edit your /etc/hostapd/hostapd.conf file like below and restart hostapd.
#WPS stuff
# Enable control interface for PBC/PIN entry
ctrl_interface=/var/run/hostapd
eap_server=1
wps_state=2
ap_setup_locked=1
wps_pin_requests=/var/run/hostapd.pin-req
config_methods=label display push_button keypad
#WPS model info stuff change to suit your needs
device_name=USB2.0 WLAN
manufacturer=ATHEROS
model_name=WAP........
If you are getting this error from systemctl "Loaded: masked (Reason: Unit hostapd.service is masked.)" we need to unmask the service.
Solution
systemctl unmask hostapd
Removed /etc/systemd/system/hostapd.service.
It's fixed
root@routerOS:/var/log# systemctl start hostapd
root@routerOS:/var/log# systemctl status hostapd
● hostapd.service - Access point and authentication server for Wi-Fi and Ethern........
iw dev wlan0 station dump
This is very useful because it is helpful if you are running something like hostapd and need to see the signal strength and negotiated connection speed.
Station ff:ff:ff:ff:ff:ff (on wlan0)
inactive time: 16309 ms
rx bytes: 25451
rx packets: 325
tx bytes: 44381
tx packets: 159
tx retries: 0
tx failed: 0
signal: -72 [-72] dBm
signal avg: -72 [-72] dBm........