/boot/wpa_supplicant.conf

network={
    ssid="SSID"
    psk="PREESHARED KEY"
    key_mgmt=WPA-PSK
}

/boot/octopi-network.txt

iface wlan0-octopi inet manual
    wpa-ssid "SSID"
    wpa-psk "PREESHARED KEY"

/etc/dhcpcd.conf

interface wlan0
static ip_address=192.168.1.200/24
static routers=192.168.1.1
static domain_name_servers=8.8.8.8