diff --git a/ostp-client/src/transport/xhttp.rs b/ostp-client/src/transport/xhttp.rs
index 6aa766d..4ede3df 100644
--- a/ostp-client/src/transport/xhttp.rs
+++ b/ostp-client/src/transport/xhttp.rs
@@ -180,8 +180,8 @@ where
     R: tokio::io::AsyncRead + Unpin + Send + 'static,
     W: tokio::io::AsyncWrite + Unpin + Send + 'static,
 {
-    let (app_tx, mut tx_rx) = mpsc::channel::<Bytes>(1024);
-    let (rx_tx, app_rx) = mpsc::channel::<Bytes>(1024);
+    let (app_tx, mut tx_rx) = mpsc::channel::<Bytes>(16384);
+    let (rx_tx, app_rx) = mpsc::channel::<Bytes>(16384);
 
     // TX Loop (App -> UoT -> Network): prefix each frame with u16 BE length
     tokio::spawn(async move {
diff --git a/ostp-server/src/relay.rs b/ostp-server/src/relay.rs
index d2b2d34..11fb81c 100644
--- a/ostp-server/src/relay.rs
+++ b/ostp-server/src/relay.rs
@@ -133,7 +133,7 @@ pub async fn handle_relay_message(
             if debug {
                 let _ = ui_event_tx.send(UiEvent::Log(format!("Relay UDP ASSOCIATE stream_id={stream_id}")));
             }
-            let server_udp = match UdpSocket::bind("0.0.0.0:0").await {
+            let server_udp = match UdpSocket::bind("[::]:0").await.or_else(|_| UdpSocket::bind("0.0.0.0:0").await) {
                 Ok(s) => std::sync::Arc::new(s),
                 Err(e) => {
                     let _ = ui_event_tx.send(UiEvent::Log(format!("UDP bind failed: {e}")));
diff --git a/ostp-server/src/transport/uot.rs b/ostp-server/src/transport/uot.rs
index ac00bcb..2ecb9ae 100644
--- a/ostp-server/src/transport/uot.rs
+++ b/ostp-server/src/transport/uot.rs
@@ -116,7 +116,7 @@ where
     info!("UoT client authenticated from {}", peer_addr);
 
     // Register this connection in the map
-    let (tx, mut rx) = mpsc::channel::<Bytes>(1024);
+    let (tx, mut rx) = mpsc::channel::<Bytes>(16384);
     {
         tcp_map.write().await.insert(peer_addr, tx);
     }