# Quick Fix Guide for "Failed to Connect to Server"

## Your Issue: Teammate sees "CONNECTED" but can't join

This is likely a **Firewall** issue even with port forwarding.

## Immediate Actions (Try in Order)

### 1. Disable Windows Firewall Temporarily (Test Only)
```
Windows Security → Firewall & network protection → Private network → Microsoft Defender Firewall: OFF
Public network → Microsoft Defender Firewall: OFF
```
Then test connection. If it works, re-enable and create specific rule for Unity.

### 2. Add Unity Exclusion to Firewall
Run these commands as Administrator in PowerShell/CMD:

```
# Allow Unity Editor
netsh advfirewall firewall add rule name="Unity Editor" dir=in action=allow program="%ProgramFiles%\Unity\Hub\Editor\*\Unity.exe" enable=yes

# Allow your built executable (replace path)
netsh advfirewall firewall add rule name="Northbound Game" dir=in action=allow program="D:\Northbound\Build\Northbound.exe" enable=yes profile=any

# Allow port 7777
netsh advfirewall firewall add rule name="Unity Port 7777" dir=in action=allow protocol=TCP localport=7777 enable=yes profile=any
```

### 3. Verify Port Forwarding is Working
Go to: https://www.yougetsignal.com/tools/open-ports/
- Enter your PUBLIC IP (what you give to teammate)
- Enter port 7777
- Click "Check Port"

**Expected:** "Port 7777 is open on [YOUR PUBLIC IP]"
**If closed:** Port forwarding is incorrect

### 4. Add Debug Scripts to Scene
Add these components to your NetworkManager GameObject:
1. **ConnectionDiagnostics** - Checks for configuration issues
2. **NetworkDebugger** - Shows detailed connection logs
3. **NetworkConnectionFixer** - Fixes common timeout issues

Right-click each and select "Run Diagnostics" or "Fix All Known Issues"

## What to Check in Console

### Host Should See:
```
✓ [NetworkConnectionFixer] Network fixes applied
✓ [ConnectionDiagnostics] System Healthy
✓ [NetworkDebugger] Server Started Successfully
✓ [NetworkDebugger] Listening on: 0.0.0.0:7777
✓ [NetworkDebugger] Client Connected: [ID]
✓ [ConnectionHandler] 클라이언트 [ID] 승인됨. 수동 스폰으로 대기.
```

### Client Should See:
```
✓ [NetworkConnectionFixer] Network fixes applied
✓ [ConnectionDiagnostics] System Healthy
✓ [NetworkDebugger] Connection Approval Request from Client [ID]
✓ [NetworkDebugger] Approval Response: Approved: true
```

## If Still Not Working

### Check These Settings:

**On NetworkManager GameObject:**
- [ ] Player Prefab assigned
- [ ] Network Prefabs list populated
- [ ] Transport component = Unity Transport (UTP)

**On Unity Transport Component:**
- [ ] ConnectionData.Port = 7777 (or your port)
- [ ] ConnectionData.Address = **0.0.0.0** for Host
- [ ] Connect Timeout MS = 15000
- [ ] Max Connect Attempts = 10

**In NetworkManager Inspector (Network Config):**
- [ ] Connection Approval = **checked**
- [ ] Enable Scene Management = **checked**

## Common Mistakes

❌ Using 127.0.0.1 or 192.168.x.x for teammate
✓ Use your PUBLIC IP for teammate

❌ Firewall blocking Unity
✓ Add exception for Unity and your game

❌ Port not actually forwarded
✓ Verify with online port checker

❌ Wrong transport address on host
✓ Host should use 0.0.0.0, client uses YOUR public IP

❌ Player prefab missing NetworkObject
✓ Ensure player prefab has NetworkObject component

## Quick Test Sequence

1. **Test Local:**
   - Start Host (connect to 127.0.0.1 from same instance)
   - If this fails: Project setup issue

2. **Test LAN:**
   - Use 192.168.x.x (local network IP)
   - If this fails: Network/Firewall issue

3. **Test Internet:**
   - Use public IP
   - If this fails: Port forwarding issue

## Console Commands for Diagnostics

Add this to a MonoBehaviour:
```csharp
[ContextMenu("Check Everything")]
void CheckEverything()
{
    Debug.Log("IsServer: " + NetworkManager.Singleton.IsServer);
    Debug.Log("IsClient: " + NetworkManager.Singleton.IsClient);
    Debug.Log("ConnectedClients: " + NetworkManager.Singleton.ConnectedClients.Count);
    Debug.Log("Local IP: " + NetworkUtility.GetLocalIPv4());
}
```

## Last Resort Solutions

1. **Use VPN/Hamachi**
   - Creates virtual LAN between you and teammate
   - No port forwarding needed
   - Both connect to VPN IP

2. **Use Unity Relay**
   - Built into Unity Netcode
   - Bypasses NAT/Firewall completely
   - Requires Unity Services account

3. **Host on Cloud Server**
   - AWS/Azure/Google Cloud
   - Static IP, no port forwarding
   - More reliable

## Share These for Help

If still broken, share:
1. Full Console log (Host and Client)
2. Screenshot: NetworkManager inspector
3. Screenshot: Unity Transport settings
4. Port checker result screenshot
5. Windows Firewall rules screenshot

---

**Most likely issue:** Windows Firewall is blocking even with port forwarding.
**Fix:** Run firewall commands in step 2.