Chat box locking up with multiple clients running

[Clunk_Head]

I solved my own problem.
I needed to make the chat_history_listbox as a ListBox initially, instead of None
I needed to put the receive code into a function, with a loop and an exit condition

def receive_func():
    global server, chat_history_listbox
    while True:
        try:
            update = server.recv(1024)
        except OSError as e:
            update = None
            break
            connect()
        msg = update.decode("utf-8")
        if msg != "":
            chat_history_listbox.insert(END, msg)

I needed to make the thread call a function and make it a daemon

listener = Thread(target=receive_func, daemon=True)
listener.start()

This got it working with multiple clients