At this stage, it is Tello (master unit) and PC (slave unit).
tello_wifi_access.py
import socket
tello_ip = '192.168.10.1'
tello_port = 8889
socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
tello_address = (tello_ip , tello_port)
socket.sendto('command'.encode('utf-8'),tello_address)
socket.sendto('ap SSID PASSWORD'.encode('utf-8'),tello_address)
Change the SSID and PASSWORD to those of the wifi to connect to.
Then Tello goes into slave mode and connects to the SSID wifi. Once set, the settings will be saved and will automatically connect to wifi the next time Tello starts.