I use the Alfa AWUS051NH USB WiFi adapter for the 2.5Ghz network of my Raspberry Pi wifi router. Thought I’d share my config file so others can quickly get up and running with this adapter.

# hostapd.conf
# see example config for more info:
#   https://w1.fi/cgit/hostap/plain/hostapd/hostapd.conf
# set region
ieee80211d=1
country_code=US
interface=WLAN-DEVICE-HERE
ssid=YOUR-WIFI-NETWORK-NAME-HERE
# 0 will choose channel with the least interference
channel=0
# g so we can use 2.4Ghz 802.11n
hw_mode=g
macaddr_acl=0
# auth_algs=1 to use open system auth:
# https://superuser.com/questions/1240876/802-11-authentication-frame-response-wrong-authentication-algorithm-detected-b/1240921
auth_algs=1
ieee80211n=1
# wpa=2 is wpa2
wpa=2
wpa_passphrase=YOUR-WIFI-PASSWORD-HERE
wpa_key_mgmt=WPA-PSK
# we want wpa2, so use CCMP
rsn_pairwise=CCMP
wmm_enabled=1
ht_capab=[GF][SHORT-GI-20][RX-STBC1]
logger_stdout=-1