The Linux wifi AP support is dire:
* rtl8192cu AP mode loses packets and connections
* rtl8xxxu does not support AP mode
* ath10k firmware crashes from time to time
* iwlwifi with hostapd 2.9 causes kernel crashes every few days with NULL pointer dereference
It seems iwlwifi with hostapd 2.8 could be the least bad option.
Revert to that version and disable problematic (insecure) CONFIG_EAP_PWD.
Sebastien Bourdeauducq