When configuring WiFi interfaces as bridge slave interfaces, they must be configured to accept a specific address mode. This is explained in https://w1.fi/cgit/hostap/plain/hostapd/hostapd.conf
# 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
This worked in VyOS 1.2 (self-built at 201808072059).