I am not fluent in English, so I’m using a translator. Please bear with me if some of the intended meaning doesn’t come across clearly.
I’m currently working on connecting a Unity TCP client and server using an external IP address obtained from Google Cloud Platform (GCP). However, despite numerous attempts, I am unable to make a successful connection with the fixed IP from GCP. I’m listing below the things I have already checked and the issues that persist. If anyone could point out any overlooked aspects or potential solutions, I would really appreciate it.
I am experiencing issues with a TCP connection in Unity using a static IP created on Google Cloud Platform (GCP). I attempted to establish a server-client connection using TCP with an external IP assigned by GCP, but after multiple tries, I am still unable to resolve the failure described below, and thus unable to use the external IP. If anyone has suggestions on what I might have overlooked, or if you have potential solutions or insights on the cause, I would greatly appreciate your help.
Confirmed Functional Components
Internal IP Address Port Forwarding: Verified NAT settings by logging into the router. Ping Test: Confirmed active network connection by pinging the GCP server’s IP from the client.
GCP Firewall Rules: Source IP Range: 0.0.0.0/0 TCP Protocol: Allowed Direction: Ingress Port and Static IP: No issues identified.
VM Instance Settings: Firewall: HTTP and HTTPS traffic allowed.
GCP SSH Remote Server Access: Successfully logged into the server with the static IP created by GCP.
Local Testing with 127.0.0.1: Local testing was successful.
Issues: Unity Error: Result: Unable to connect due to the target computer actively refusing the connection.
Attempts to Disable Windows Firewall: Tried disabling Windows Firewall but encountered the same failure. Client Code Execution Delay: Delayed client code execution by 5 seconds to ensure the server starts first, but no change in outcome.
Unity Source Code Setup: The server and client codes were assigned to separate components on empty GameObjects in Unity.
Server.cs
using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;
using UnityEngine;
using System;
using System.IO;
public class Server : MonoBehaviour
{
List<ServerClient> clients;
List<ServerClient> disconnectList;
TcpListener server;
bool serverStarted;
private const int PORT = 8000; // Set port number
private const string IP_ADDRESS = "0.0.0.0"; // Allow connections from all IPs
public void ServerCreate()
{
clients = new List<ServerClient>();
disconnectList = new List<ServerClient>();
try
{
server = new TcpListener(IPAddress.Parse(IP_ADDRESS), PORT);
server.Start();
Debug.Log($"Server started on port {PORT}.");
StartListening();
serverStarted = true;
}
catch (Exception e)
{
Debug.LogException(e);
}
}
void Start()
{
ServerCreate();
}
void Update()
{
if (!serverStarted) return;
foreach (ServerClient c in clients)
{
if (!IsConnected(c.tcp))
{
c.tcp.Close();
disconnectList.Add(c);
continue;
}
else
{
NetworkStream s = c.tcp.GetStream();
if (s.DataAvailable)
{
string data = new StreamReader(s, true).ReadLine();
if (data != null)
OnIncomingData(c, data);
}
}
}
for (int i = 0; i < disconnectList.Count; i++)
{
Debug.Log($"{disconnectList[i].clientName} disconnected.");
clients.Remove(disconnectList[i]);
disconnectList.RemoveAt(i);
}
}
bool IsConnected(TcpClient c)
{
try
{
if (c != null && c.Client != null && c.Client.Connected)
{
if (c.Client.Poll(0, SelectMode.SelectRead))
return !(c.Client.Receive(new byte[1], SocketFlags.Peek) == 0);
return true;
}
else
return false;
}
catch
{
return false;
}
}
void StartListening()
{
server.BeginAcceptTcpClient(AcceptTcpClient, server);
}
void AcceptTcpClient(IAsyncResult ar)
{
TcpListener listener = (TcpListener)ar.AsyncState;
ServerClient newClient = new ServerClient(listener.EndAcceptTcpClient(ar));
clients.Add(newClient);
Debug.Log($"Client connected: {newClient.clientName}");
StartListening();
}
void OnIncomingData(ServerClient c, string data)
{
if (data.Contains("&NAME"))
{
c.clientName = data.Split('|')[1];
Debug.Log($"{c.clientName} connected.");
return;
}
}
public void Broadcast(string data, List<ServerClient> cl)
{
foreach (var c in cl)
{
try
{
StreamWriter writer = new StreamWriter(c.tcp.GetStream());
writer.WriteLine(data);
writer.Flush();
}
catch (Exception e)
{
Debug.LogException(e);
}
}
}
}
public class ServerClient
{
public TcpClient tcp;
public string clientName;
public ServerClient(TcpClient clientSocket)
{
clientName = "Guest";
tcp = clientSocket;
}
}
Client.cs
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Net.Sockets;
using System.IO;
using System;
public class Client : MonoBehaviour
{
bool socketReady;
TcpClient socket;
NetworkStream stream;
StreamWriter writer;
StreamReader reader;
private const string SERVER_IP = "34.64.217.7"; // GCP Static IP
private const int SERVER_PORT = 8000; // Client port number
public void ConnectToServer()
{
if (socketReady) return;
try
{
socket = new TcpClient(SERVER_IP, SERVER_PORT);
stream = socket.GetStream();
writer = new StreamWriter(stream);
reader = new StreamReader(stream);
socketReady = true;
Debug.Log("Connected to server.");
SendClientName("Guest" + UnityEngine.Random.Range(1000, 10000)); // Random client name
}
catch (Exception e)
{
Debug.Log($"Socket error: {e.Message}");
}
}
void Start()
{
StartCoroutine(ConnectAfterDelay());
}
private IEnumerator ConnectAfterDelay()
{
yield return new WaitForSeconds(5); // Delay to allow server startup
ConnectToServer();
}
void Update()
{
if (socketReady && stream.DataAvailable)
{
string data = reader.ReadLine();
if (data != null)
Debug.Log(data); // Display received data
}
}
void SendClientName(string clientName)
{
Send($"&NAME|{clientName}");
}
void Send(string data)
{
if (!socketReady) return;
writer.WriteLine(data);
writer.Flush();
}
void OnApplicationQuit()
{
CloseSocket();
}
void CloseSocket()
{
if (!socketReady) return;
writer.Close();
reader.Close();
socket.Close();
socketReady = false;
}
}
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