I have a python code that is reliable implementation of UDP for messages. I am having problems with reliability, but can’t figure out what is wrong. I will post the listening part of the code and the sending part and other parts that are relevant.

def packeting(s):
    L = []
    sprime = s.split()
    seqnum = 0
    for k in sprime:
        L.append((k, seqnum))
        seqnum += 1

    return L


seqnum_received = 0  


def listen():
    print("Listening: ... ")
    L = []
    seqnumwanted = 0  
    while True:
        try:
            messagerec, clientAddress = serverSocket1.recvfrom(2048)
            msg = messagerec.decode()
            message = eval(msg)  
            global seqnum_received
            if type(message) == tuple:  
                seqnum_received = message[1]  
                if seqnum_received == seqnumwanted:  

                    serverSocket1.sendto(str(seqnum_received + 1).encode(), ("127.0.0.1", 12000))
                    L.append(message[0])

                    seqnumwanted += 1  
                else:
                    
                    serverSocket1.sendto(str(seqnumwanted).encode(), ("127.0.0.1", 12000))  
            elif type(message) == bool and message == True:
                chatbox.insert(tk.END, "n||Peer: " + " ".join(L))  
                L = []
                seqnumwanted = 0
                seqnum_received = 0
            elif type(message) == int:
                seqnum_received = message

        except Exception as e:
            print(e)


def send():
    rawmsg = message_entry.get()
    if os.path.exists(rawmsg):    
        send_file(client_socket , rawmsg)
    else:   
        packets = packeting(rawmsg)  
        for packet in packets:
            while True:
                x = str(packet)  
                serverSocket1.sendto(x.encode(), ("127.0.0.1", 12000))
                try:
                    if seqnum_received == packet[1] + 1:
                        break
                except Exception as e:
                    print(e)
        serverSocket1.sendto(str(True).encode(), ("127.0.0.1", 12000))  
        chatbox.insert(tk.END , "n|You: " + rawmsg)
        message_entry.delete(0, tk.END)

When testing on a noisy channel, the messages were not getting through.