Answer
You must load Summit firmware for multi-BSSID support. After loading the driver and firmware, perform the following: Stop all software that may be managing the Wi-Fi interface including the supplicant, NetworkManager, connman, hostapd, etc.
List out the current virtual interfaces on the physical interface (phy):
# iw dev phy#0 Interface wlan0 ifindex 7 wdev 0x1 addr c0:ee:40:50:00:00 type managed txpower 20.00 dBm
Delete the virtual interface:
# iw wlan0 del
Add up to 3 virtual interfaces onto the phy using unique names per dev (note there are two underscores in __ap):
# iw phy0 interface add ap0 type __ap # iw phy0 interface add ap1 type __ap # iw phy0 interface add ap2 type __ap
Confirm the virtual interfaces exist:
# iw dev phy#0 Interface ap2 ifindex 10 wdev 0x4 addr c0:ee:40:50:00:02 type AP txpower 20.00 dBm Interface ap1 ifindex 9 wdev 0x3 addr c0:ee:40:50:00:01 type AP txpower 20.00 dBm Interface ap0 ifindex 8 wdev 0x2 addr c0:ee:40:50:00:00 type AP txpower 20.00 dBm
The MAC on the first interface will not change and each subsequent interface added will add 1 to the first MAC.