android phone often needs reboot to authenticate with 802.11ac AP

[Bruno Dantas]

Greetings, wifi gurus. I need some help and don't know where else to ask. Hopefully one of you can point me in the right direction.

My home's wireless router is a homebrewed x86_64 GNU+Linux machine running linux 6.6.8 and hostapd 2.11. The AP is created using an Alfa AWUS036ACHM usb adapter. I've been happily using this router with the following hostapd configuration for many years with no problems whatsoever:

ssid=homesweet_home
interface=wlan1
driver=nl80211
country_code=US
channel=44
ignore_broadcast_ssid=0
hw_mode=a
auth_algs=1
wpa=2
wpa_passphrase=4thornberry
wpa_key_mgmt=WPA-PSK
wpa_pairwise=CCMP
rsn_pairwise=CCMP
ieee80211n=1
wmm_enabled=1
ht_capab=[HT40+][HT40-][SHORT-GI-20][SHORT-GI-40]

Recently I decided to tweak the hostapd configuration so that my AP supports 802.11ac. This is my new configuration:

ssid=homesweet_home
interface=wlan1
driver=nl80211
country_code=US
channel=36
ignore_broadcast_ssid=0
hw_mode=a
auth_algs=1
wpa=2
wpa_passphrase=4thornberry
wpa_key_mgmt=WPA-PSK
wpa_pairwise=CCMP
rsn_pairwise=CCMP
ieee80211n=1
wmm_enabled=1
ht_capab=[HT40+][HT40-][SHORT-GI-20][SHORT-GI-40] # I also tried adding [GF]
vht_oper_chwidth=1
vht_oper_centr_freq_seg0_idx=42
ieee80211ac=1
vht_capab=[SHORT-GI-80] # I also tried adding [MAX-A-MPDU-LEN-EXP3][RX-ANTENNA-PATTERN][TX-ANTENNA-PATTERN] per morrownr's github

Everything works with this new hostapd.conf except one thing: When I return home from work, my Android phone (rooted OnePlus 5 with LineageOS 16) is sometimes unable to authenticate with my AP: The phone says "Connecting..." then "Saved" by my SSID several times, eventually says my SSID is "Disabled." Toggling wifi off and back on doesn't help. Forgetting the SSID and re-entering password doesn't help. Toggling "Airplane Mode" off and on doesn't help. To authenticate with my AP again, I have to reboot my phone.

Can anyone think of an explanation why my phone has no trouble authenticating with my AP using the old (802.11n) hostapd.conf, but often needs a reboot before it can authenticate with the same AP using the new (802.11ac) hostapd.conf? Since I control the AP as well as the rooted phone, I can change settings on either end (or both ends) to make authentication reliable. I just need some guidance because I've tried everything I can think of to no avail.