I've been using this guide
I've setup a Raspberry Pi 3+ which has a WiFi dongle and onboard WiFi to do this. The WiFi dongle is an AC600 with the 8812au chipset, requiring compiled kernel drivers, which I compiled installed. This is my wlan0, the onboard chipset is wlan1.
When I follow your guide and use the onboard as the AP, everything works fine. However, when I switch them around, and try to use wlan0 as my AP (which is the intention), then the access point doesn't get setup. When I inspect the journal I find:
Mar 13 15:53:14 HTL wpa_supplicant: nl80211: Could not configure driver mode Mar 13 15:53:14 HTL wpa_supplicant: nl80211: deinit ifname=wlan0 disabled_11b_rates=0
It seems wpa_supplicant is trying to load the nl80211 driver instead of the 8812au driver?
Is there a way to fix this?