@Quardah If I'm not mistaken, since version 6.1.1, it is possible to edit the ip manually in the recalbox.conf file:
## Wifi - static IP
## if you want a static IP address, you must set all 3 values (ip, gateway, and netmask)
## if any value is missing or all lines are commented out, it will fall back to the
## default of DHCP
wifi.ip =
It is much easier now, the tutorial you are following is probably out of date.