UDP Client does not EVER receive packets back!

I am sending packets back to the client, from the server but he never gets them. He is bind on port 8000 and server is bind on 8080. I use Tokio, and I send the packet back with:

  thread_socket.send_to(&*missing_chunks, ADDRESS_CLIENT).await;

I init the socket on the server side with

let socket_out = UdpSocket::bind(ADDRESS_OUT).await.unwrap();
let arc_out = Arc::new(socket_out);
let thread_socket = arc_out.clone();

(ideally I wanted to use let arc= = Arc::new(socket); let thread_socket = arc.clone(); but I get the error with generator: -- variable moved due to use in generator and value borrowed here after move and after 3h of pointless coding I decided to rage quit with this fix trying many things I have still no idea how to fix it so I thought " Okay I might just create another port then..." )

on the client side I wait for the packets with

let len:usize = socket.recv(&mut buffer).await.unwrap();

I init the socket on client side with

let remote_addr: SocketAddr = env::args()
        .unwrap_or_else(|| "".into()) // cargo run --example udp-client --

    // We use port 0 to let the operating system allocate an available port for us.
    let local_addr: SocketAddr = if remote_addr.is_ipv4() {
       ""// "" //
    } else {
let socket = UdpSocket::bind(local_addr).await?;
  • This is where I have the difficulties on the server side: althought it says that the data is sent.
  • This is where I am awaiting the server packets on the client side (and they never arrive)

I really want to scream "HELP HELP please please" but I will try to preserve some dignity after 2 days of worthless coding :< Any help really strongly appreciated, willing to sell my soul for it.

If you're unsure whether the basic communication works at all, it helps to start with a really bare-bones implementation and expand from that. Here is a combined client/server program which sends a UDP packet with an increasing sequence number every second (in server mode, srv as the first argument), and receives those packets and prints them out (in client mode, no arguments):

// tokio = { version = "1", features = ["full"] }

use std::env;
use std::error::Error;
use std::net::SocketAddr;
use std::process;
use std::time::Duration;

use tokio::net::UdpSocket;
use tokio::time::sleep;

#[derive(Clone, Debug)]
enum Mode {

async fn main() -> Result<(), Box<dyn Error>> {
    let mode = match env::args().nth(1) {
        None => Mode::Client,
        Some(ref m) if m == "srv" => Mode::Server,
        _ => {
            eprintln!("Usage: udpsc [srv]");
    match mode {
        Mode::Client => do_client().await,
        Mode::Server => do_server().await,

async fn do_client() -> Result<(), Box<dyn Error>> {
    let cli = UdpSocket::bind("").await?;
    let mut buf = [0u8; 16];
    loop {
        match cli.recv(&mut buf).await {
            Ok(_) => if let Ok(s) = std::str::from_utf8(&buf[..]) {
                println!("{}", s);
            Err(e) => eprintln!("recv error: {}", e),

async fn do_server() -> Result<(), Box<dyn Error>> {
    let srv = UdpSocket::bind("").await?;
    let client: SocketAddr = "".parse()?;
    let mut seq = 0;
    loop {
        let _ = srv.send_to(format!("seq: {}", seq).as_bytes(), &client).await;
        seq += 1;

Run the server first, in background, then run the client.

Thank you I have run it and it worked very well. Problem is that I already started from a basic example and expanded from it. To be precise I think my problem stems from the debouncer where I dont find a way to clone the socket .

See below schema

client bind to a port and bind to server
udp packets (with file bytes) sent from client 
server receives the bytes and request missing packets to client
client process message from server to resend packets

So its between those twos that I fail, but when I look at my code, even with the println, it is hard to understand why its not working.

Edit: I found that the culprit was because of the second socket (socket_out) being created but not connected. My problem is that I cannot use the former arc socket in the generator function. If I comment this line the programs compile but my goal is exactly to be able to send the message.

If I uncomment and move let thread_socket = arc.clone(); before 'let _debouncer' then I have this error message (that is driving me nuts):

error[E0382]: borrow of moved value: `thread_socket`
   --> src/server/bin/main.rs:220:18
165 |   let thread_socket = arc.clone();
    |       ------------- move occurs because `thread_socket` has type `std::sync::Arc<tokio::net::UdpSocket>`, which does not implement the `Copy` trait
166 |       let _debouncer = task::spawn(async move {
    |  _____________________________________________-
167 | |
168 | |         let duration = Duration::from_millis(1300);
169 | |
...   |
204 | |                         thread_socket.send_to(&*missing_chunks, ADDRESS_CLIENT).await; // arc_out.clone().send_to(&*missing_chunks, &peer...
    | |                         ------------- variable moved due to use in generator
...   |
216 | |         }
217 | |     });
    | |_____- value moved here
220 |       let result = thread_socket.recv_from(&mut buf).await;
    |                    ^^^^^^^^^^^^^ value borrowed here after move

error: aborting due to previous error

How could I enable Arc(socket) inside the generator function?

The error message is actually fairly clear here: You're attempting to use thread_socket on L220 after it was moved into the async move { and using it on L204. Arc does not implement Copy, so you have to clone it in this case. If you replace thread_socket with arc.clone() directly, it should work fine.

Actually yes and no, the problem was that I already had another clone, I found the fix: it was to have it in another scope with { }

I had a look at your updated code and the block is useless. The real fix was re-cloning it on L250.

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you are right, I just tested, indeed!

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