Setting the antenna count for recent WiFi adapters requires to set multiple flags.
https://w1.fi/cgit/hostap/plain/hostapd/hostapd.conf
# vht_capab: VHT capabilities (list of flags) # [...] # Compressed Steering Number of Beamformer Antennas Supported: # [BF-ANTENNA-2] [BF-ANTENNA-3] [BF-ANTENNA-4] # Beamformee's capability indicating the maximum number of beamformer # antennas the beamformee can support when sending compressed beamforming # feedback # If SU beamformer capable, set to maximum value minus 1 # else reserved (default) # # Number of Sounding Dimensions: # [SOUNDING-DIMENSION-2] [SOUNDING-DIMENSION-3] [SOUNDING-DIMENSION-4] # Beamformer's capability indicating the maximum value of the NUM_STS parameter # in the TXVECTOR of a VHT NDP # If SU beamformer capable, set to maximum value minus 1 # else reserved (default)
This does not work in VyOS 1.3.
This worked in VyOS 1.2 (self-built at 201808072059).