vyos@apu2# set interfaces bridge br0 vif 100 address 10.66.66.254/24
[edit]
vyos@apu2# compare
[interfaces bridge br0]
+ vif 100 {
+     address "10.66.66.254/24"
+ }

[edit]
vyos@apu2# commit

You must first activate "enable-vlan" of br0 bridge to use "vif"

[[interfaces bridge br0]] failed
Commit failed
[edit]
vyos@apu2# discard

  Changes have been discarded

[edit]
vyos@apu2# set interfaces bridge br0 enable-vlan
[edit]
vyos@apu2# compare
[interfaces bridge br0]
+ enable-vlan

[edit]
vyos@apu2# commit

Can not add interface "wlan0" to bridge, VLAN aware cannot be set!

[[interfaces bridge br0]] failed
Commit failed
[edit]
vyos@apu2#

# For nl80211, this parameter can be used to request the AP interface to be
# added to the bridge automatically (brctl may refuse to do this before hostapd
# has been started to change the interface mode). If needed, the bridge
# interface is also created.
#bridge=br0

# WDS (4-address frame) mode with per-station virtual interfaces
# (only supported with driver=nl80211)
# This mode allows associated stations to use 4-address frames to allow layer 2
# bridging to be used.
#wds_sta=1