How do I fix UDP hole punching not working in my program?

Question

I've been trying to test UDP hole punching in Python and it seems that the message is not received by the other client.

Is there a possible solution to this?

Here is the code:

from socket import *
from _thread import start_new_thread

from sys import argv

from time import sleep

PORT = 50000 + int(argv[1])

sock = socket(AF_INET, SOCK_DGRAM)

sock.bind(("0.0.0.0", PORT))

def read():
    while True:
        print(sock.recvfrom(1024))

start_new_thread(read, ())

while True:
    sock.sendto(b"0", ("<my ip>", [50002, 50001][PORT-50001]))
    sleep(1)

Both are on the same network, as I do not own multiple networks to test, but are attempting to communicate through the public IP, but they do not seem to actually receive the message. I expected to receive messages and establish a hole punch, but it does not seem like that is working.