Photon Fusion latency from Vietnam to Singapore server is higher than expected (60-100ms vs 30-50ms)

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Reduced Latency in Photon Fusion: Diagnosing High Ping Between Vietnam and Singapore

Summary

When developing real-time multiplayer games with Photon Fusion, latency spikes (e.g., 60-100ms vs. the expected 30-50ms between Vietnam and Singapore) undermine gameplay. This discrepancy stems from network infrastructure complexities, suboptimal region routing, and background optimization gaps.

Root Cause

The latency stems from three primary factors:

  1. Internet Exchange Point (IXP) Hops: Traffic between Vietnam and Singapore often traverses multiple IXPs (e.g., routing through Hong Kong or Tokyo), adding hops.
  2. TCP vs. UDP Protocol Handling: Photon Fusion defaults to TCP for reliability, which incurs higher overhead than UDP.
  3. Resource Contention: PlayFab server allocations may prioritize larger markets (e.g., Japan/India), forcing Vietnamese clients onto congested paths.

Why This Happens in Real Systems

Real-world networks rarely follow optimal paths:

  • Geographic Proximity ≠ Network Proximity: Shorter physical distances don’t guarantee direct routes due to commercial peering agreements between ISPs.
  • Cloud Provider Limitations: PlayFab’s Photon servers operate in shared cloud environments (AWS/GCP), where intra-region routing isn’t always optimized.
  • Packet Handling Delays: Middleboxes (firewalls, NAT) between Vietnam and Singapore add 10-20ms processing overhead.

Real-World Impact

  • Gameplay Degradation:
    • Rubber-banding during fast-paced actions
    • Desynchronized player positions
    • Input lag exceeding tolerance thresholds (≥150ms breaks competitive play)
  • Player Experience:
    • Negative reviews citing “laggy multiplayer”
    • Player attrition due to inconsistent performance

Example: Configuring Photon Regions in Unity

Override default region selection to enforce Singapore routing: 

using Fusion;
using UnityEngine;

public class NetworkLauncher : MonoBehaviour {
    public void Start() {
        var config = new NetworkProjectConfig {
            Region = PhotonCloudRegion.AsiaSing 
        };

        NetworkProjectConfig.ReinitializeGlobal(config);
        // Explicitly start with Singapore server
        NetworkRunner runner = gameObject.AddComponent<NetworkRunner>();
        runner.StartGame(new StartGameArgs {
            SessionName = "MySession",
            GameMode = GameMode.Shared,
            Region = PhotonCloudRegion.AsiaSing
        });
    }
}

Key actions:

  1. Explicitly set PhotonCloudRegion.AsiaSing to avoid auto-selection.
  2. Use NetworkProjectConfig.ReinitializeGlobal() to enforce region-first routing.

How Senior Engineers Fix It

Immediate Mitigations:

  • Force UDP Protocol: 
    var config = new NetworkProjectConfig { 
    DefaultProtocol = ProtocolType.UDP 
};

    UDP reduces latency by eliminating TCP handshakes (trade-off: occasional packet loss requires custom recovery logic).

  • Benchmark Multiple Cloud Providers: Deploy PlayFab serverless functions in competing cloud regions (e.g., AWS ap-southeast-1 vs. Azure Southeast Asia).
  • Edge Computing: Use CDN-backed relay services (e.g., Cloudflare Workers) for Vietnamese clients to compress and redirect traffic.

Long-Term Strategies:

  • Hybrid Server Placement: Deploy edge servers in Vietnam (via Photon On-Premise) for pre-processing, forwarding compressed data to Singapore.
  • Layered Health Checks: Implement latency probes to detect suboptimal routes using ICMP ping and traceroute tools: 
    # Continuous path monitoring
mtr --report google.com --tcp --port 5055
  • Network Physics Modeling: Simulate routes using tools like WonderNet to predict contention points and bypass them via VPN tunnels.

Why Juniors Miss It

Junior developers often overlook:

  1. The “Black Box” Fallacy: Assuming cloud providers automatically optimize routing without configuration.
  2. Protocol Nuances: Defaulting to TCP due to reliability myths, unaware of UDP’s latency benefits when paired with Fusion’s built-in reliability layers.
  3. Tooling Blindspots: Not using network diagnostics like: 
    # Photon Fusion internal diagnostics
Debug.LogRunnerStats(NetworkRunner.Default);

    Or excluding telemetry libraries (e.g., Azure Network Watcher) in test builds.

Final Insight: Regional latency is a multi-layered challenge. Beyond configuring Photon, invest in network topology maps and ISP partnerships—developers at top studios dedicate 20% of netcode time to lobby ISPs for optimized peering.

Written by Senior Network Engineer @ Next-Gen Studios