diff --git a/Assets/NetworkLobbyClient/Runtime/LobbyClient.dll b/Assets/NetworkLobbyClient/Runtime/LobbyClient.dll
index f867f38..8956247 100644
Binary files a/Assets/NetworkLobbyClient/Runtime/LobbyClient.dll and b/Assets/NetworkLobbyClient/Runtime/LobbyClient.dll differ
diff --git a/Assets/NetworkLobbyClient/Runtime/LobbyServerDto.dll b/Assets/NetworkLobbyClient/Runtime/LobbyServerDto.dll
index 1646bfd..7b5acc4 100644
Binary files a/Assets/NetworkLobbyClient/Runtime/LobbyServerDto.dll and b/Assets/NetworkLobbyClient/Runtime/LobbyServerDto.dll differ
diff --git a/LobbyClient/LobbyClient.cs b/LobbyClient/LobbyClient.cs
index caf24bf..c5ed145 100644
--- a/LobbyClient/LobbyClient.cs
+++ b/LobbyClient/LobbyClient.cs
@@ -173,21 +173,23 @@ namespace Lobbies
         /// <param name="lobbyId">The lobby to request a nat punch for</param>
         /// <param name="password">Optional password of lobby</param>
         /// <param name="port">The port the game client will later use. We create a udp socket on it and send a packet to the lobby server to get the firewall to map that port for a short period of time
-        /// after that the udp client will be disposed</param>
-        public void RequestLobbyNatPunch(Guid lobbyId, string? password, int port = 0)
+        /// after that the udp client will be disposed.</param>
+        public int RequestLobbyNatPunch(Guid lobbyId, string? password, int port = 0)
         {
+            if(port < 0 && port > 65535)
+                throw new ArgumentOutOfRangeException(nameof(port));
+
             byte[]? passwordHash = null;
             if (!string.IsNullOrEmpty(password) && lobbyInformation.ContainsKey(lobbyId) && lobbyInformation[lobbyId].PasswordSalt != null)
                 passwordHash = PasswordHash.Hash(password, lobbyInformation[lobbyId].PasswordSalt!);
 
-            Task.Run(() =>
-            {
-                using (var udpEchoServer = new UdpEchoServer())
-                {
-                    udpEchoServer.Start(port);
-                    QueryExternalIpAndPort(udpEchoServer.Send);
-                }
+            var udpEchoServer = new UdpEchoServer();
+            udpEchoServer.Start(port);
 
+            Task.Run(() =>
+            {                    
+                QueryExternalIpAndPort(udpEchoServer.Send);
+                udpEchoServer.Dispose();
                 var lobbyRequestNatPunch = new LobbyRequestNatPunch()
                 {
                     LobbyId = lobbyId,
@@ -200,6 +202,8 @@ namespace Lobbies
                 var len = lobbyRequestNatPunch.Serialize(messageData);
                 _ = Task.Run(async () => { await tcpClient.Send(messageData, 0, len); bufferRental.Return(messageData); });
             });
+
+            return udpEchoServer.Port;
         }
 
         public void UpdateLobby(string name, int gameMode, int maxPlayerCount, int playerCount, string? password, int port)
@@ -381,6 +385,16 @@ namespace Lobbies
                 {
                     switch (LobbyMessageIdentifier.ReadLobbyMessageIdentifier(data.Span))
                     {
+                        case LobbyNotFound.TypeId:
+                            {
+                                events.Enqueue(new LobbyClientEvent { EventType = LobbyClientEventTypes.LobbyJoinFailed, EventData = new LobbyJoinFailReason { Reason = LobbyJoinFailReason.FailReasons.LobbyNotFound, ErrorMessage = string.Empty } });
+                            }
+                            break;
+                        case LobbyWrongPassword.TypeId:
+                            {
+                                events.Enqueue(new LobbyClientEvent { EventType = LobbyClientEventTypes.LobbyJoinFailed, EventData = new LobbyJoinFailReason { Reason = LobbyJoinFailReason.FailReasons.WrongPassword, ErrorMessage = string.Empty } });
+                            }
+                            break;
                         case LobbyClientConnectionInfo.TypeId:
                             {
                                 var lobbyClientConnectionInfo = LobbyClientConnectionInfo.Deserialize(data.Span);
diff --git a/LobbyClient/LobbyClientEvent.cs b/LobbyClient/LobbyClientEvent.cs
index 69f78f5..430631e 100644
--- a/LobbyClient/LobbyClientEvent.cs
+++ b/LobbyClient/LobbyClientEvent.cs
@@ -63,6 +63,10 @@
         /// <summary>
         /// A direct connection test without a nat punch was testet. EventData is <see cref="DirectConnectionResultTest"/> with information if a direct connection was possible and on what address.
         /// </summary>
-        DirectConnectionTestComplete
+        DirectConnectionTestComplete,
+        /// <summary>
+        /// A join request to a lobby has failed. EventData is <see cref="LobbyJoinFailReason"/> with information about the failure.
+        /// </summary>
+        LobbyJoinFailed,
     }
 }
diff --git a/LobbyClient/LobbyJoinFailReason.cs b/LobbyClient/LobbyJoinFailReason.cs
new file mode 100644
index 0000000..f2b14c2
--- /dev/null
+++ b/LobbyClient/LobbyJoinFailReason.cs
@@ -0,0 +1,19 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Lobbies
+{
+    public class LobbyJoinFailReason
+    {
+        public enum FailReasons
+        {
+            WrongPassword,
+            LobbyNotFound,
+            LobbyFull
+        }
+
+        public FailReasons Reason { get; internal set; }
+        public string? ErrorMessage { get; internal set; }
+    }
+}
diff --git a/LobbyClient/UdpEchoServer.cs b/LobbyClient/UdpEchoServer.cs
index b00d937..81020cf 100644
--- a/LobbyClient/UdpEchoServer.cs
+++ b/LobbyClient/UdpEchoServer.cs
@@ -198,6 +198,7 @@ namespace Lobbies
             if (!isDisposed)
             {
                 Stop();
+
                 while (isRunningV4 || isRunningV6)
                     Task.Yield();
 
diff --git a/LobbyServer/Program.cs b/LobbyServer/Program.cs
index 9aa1bb6..67fd490 100644
--- a/LobbyServer/Program.cs
+++ b/LobbyServer/Program.cs
@@ -243,6 +243,18 @@ tcpServer.DataReceived += (clientId, dataLength, data) =>
                                 });
                             }
                         }
+                        else
+                        {
+                            var messageData = bufferRental.Rent();
+                            var lobbyNotFound = new LobbyNotFound() { LobbyId = lobbyRequestHostInfo.LobbyId };
+                            var messageDataLength = lobbyNotFound.Serialize(messageData);
+                            _ = Task.Run(async () => {
+                                await tcpServer.Send(clientId, messageData, 0, messageDataLength);
+                                bufferRental.Return(messageData);
+                            });
+
+                            return;
+                        }
                     }
                 }
                 break;
diff --git a/LobbyServerDto/LobbyNotFound.cs b/LobbyServerDto/LobbyNotFound.cs
new file mode 100644
index 0000000..8682f7d
--- /dev/null
+++ b/LobbyServerDto/LobbyNotFound.cs
@@ -0,0 +1,14 @@
+namespace LobbyServerDto
+{
+    /// <summary>
+    /// Send if a client requests information about a password protected lobby with an invalid password hash
+    /// </summary>
+    [LobbyMessage]
+    public partial class LobbyNotFound
+    {
+        /// <summary>
+        /// Id of the lobby
+        /// </summary>
+        public Guid LobbyId { get; set; }
+    }
+}
\ No newline at end of file