Helldivers 2 uses a hybrid networking model where part of the connection is peer-to-peer rather than fully server-authoritative, which means firewall and NAT behavior on your specific router can matter as much as — or more than — which DNS resolver you use.
Understanding Helldivers 2 Hybrid P2P Architecture
Unlike dedicated server titles where all players connect to a central data center, in Helldivers 2, one player in the squad acts as the mission host:
- Your client queries backend DNS to resolve Sony/Steam matchmaking APIs and discover available galactic missions.
- To connect to the host player's PC or PS5 console behind their home router, your client sends UDP packets to STUN (Session Traversal Utilities for NAT) servers to punch through NAT firewalls.
- If your DNS resolver is slow or returns outdated STUN endpoint addresses, the handshake times out, and the game displays 'Failed to Join Lobby'.
Understanding STUN / TURN NAT Traversal in Peer-to-Peer Squads
In Helldivers 2, when you join a friend's active mission, your game client does not connect to a Sony or Arrowhead dedicated game server; it connects directly to the squad host's PlayStation 5 or PC. Because both players are behind home firewalls, the game utilizes STUN (Session Traversal Utilities for NAT / RFC 5389) servers to discover your external public IP and port binding.
If your DNS resolver is slow to resolve STUN endpoints, or if AT&T's security filters intercept the incoming UDP hole-punching packets, the connection handshake times out after 10 seconds, and you receive the error: 'Connection to Host Lost / Failed to Join Lobby'.
Port Forwarding Guide for Helldivers 2 (PC & PS5)
To guarantee an open NAT type for Helldivers 2 squad hosting, forward these ports in your router settings:
| Platform | Protocol | Port Range |
|---|---|---|
| PC (Steam) | UDP | 27015 – 27030, 3478, 4379, 4380 |
| PC (Steam) | TCP | 27014 – 27050 |
| PlayStation 5 | UDP | 3074, 3478 – 3479 |
| PlayStation 5 | TCP | 80, 443, 3478 – 3480 |
Crossplay Connectivity: PC Steam & PlayStation 5 Squad Harmony
Helldivers 2 features complete crossplay between Steam PC players and PS5 console gamers. Crossplay requires continuous cryptographic token exchanges between Sony Interactive Entertainment (SIE) PlayStation Network APIs and Valve Steam servers:
- PSN Authentication Token Resolution: When a PS5 squad leader invites a PC player, both clients resolve Sony's global auth endpoints to validate crossplay permissions.
- STUN NAT Traversal Matching: The squad negotiates UDP socket hole-punching. When both clients use Cloudflare (
1.1.1.1) or Google (8.8.8.8), DNS query response times match perfectly, preventing session handshake mismatch errors.
Network Health Checklist for Helldivers 2 Missions
- Verify Open NAT / Type 2 NAT on PlayStation 5 and PC.
- Disable IPv6 on Problematic Routers if experiencing random mid-mission drops (some ISP IPv6 routing tables have broken P2P MTU discovery).
- Use Hardwired Cat6 Ethernet instead of 5 GHz Wi-Fi to eliminate radio interference during heavy planetary explosions.
Why Planetary Mission Drops Require Symmetric Fiber Bandwidth
During intense Helldivers 2 missions on higher difficulty tiers (Suicide Mission, Impossible, Helldive), hundreds of enemy Terminids or Automatons spawn simultaneously alongside orbital strikes, Eagle 500kg bombs, and sentry turrets. The squad host's PC must constantly broadcast physical ragdoll positions and enemy AI state vectors to all three squadmates over UDP.
On AT&T Fiber's symmetrical upload connection paired with Cloudflare DNS (1.1.1.1), outbound squad synchronization packets transmit in under 4 milliseconds with zero packet drops, ensuring that Bile Titans and Factory Striders track smoothly on every player's screen with zero desync.
Summary Diagnostic Checklist for Helldivers 2 Squads
- Set DNS to
1.1.1.1(Preferred) and8.8.8.8(Alternate). - Ensure AT&T ActiveArmor is disabled in Smart Home Manager.
- Verify UPnP is enabled in router firmware.
- Hardwire your PS5 or PC via Cat6 Ethernet cable.
Step-by-Step Fix for Helldivers 2 on AT&T Fiber
- Disable AT&T ActiveArmor Security: Open the AT&T Smart Home Manager app on your phone, navigate to Security, and disable ActiveArmor Internet Security. This stops the gateway from misidentifying P2P squad packets as malicious attacks.
- Set Custom DNS (Cloudflare 1.1.1.1 / Google 8.8.8.8): On your Windows PC or PS5 network settings, manually set DNS to Primary
1.1.1.1and Secondary8.8.8.8. - Enable UPnP on Your Router: Ensure Universal Plug and Play (UPnP) is active so Helldivers 2 can dynamically map UDP ports for incoming squad handshakes.
Understanding Sony PSN Voice Chat NAT Traversals
In Helldivers 2 squad missions, team voice chat is routed over Sony's WebRTC peer-to-peer audio channels. When AT&T ActiveArmor or unoptimized DNS introduces packet delays, voice packets arrive fragmented, leading to robotic voice distortion. Configuring Cloudflare DNS (1.1.1.1) and disabling ActiveArmor security ensures voice packets and game physics maintain synchronized zero-delay delivery.
Why UPnP (Universal Plug and Play) Matters for P2P Co-Op
Universal Plug and Play (UPnP) allows gaming clients like Helldivers 2 to automatically request the router to open specific incoming UDP listening ports on demand. When UPnP is disabled in your router firewall, the game must rely on symmetric NAT traversal, which fails if both the squad host and the joining player have restrictive firewall settings. Enabling UPnP in your router's advanced settings guarantees an Open NAT status for all squad members.
Summary Recommendation for Helldivers 2 Squads
To permanently eradicate 'Failed to Join Game Lobby' errors in Helldivers 2 on AT&T Fiber: disable AT&T ActiveArmor in the Smart Home Manager app, set custom DNS to Cloudflare (1.1.1.1) on PC or PS5, and verify UPnP is active in router settings for flawless 4-player galactic squad coordination.
Why Real-World Results Vary More Than a Single Number Can Show
Network performance depends on enough site-specific and route-specific variables — your ISP's local infrastructure, distance to the nearest node, time of day, interference, and the specific path packets take — that a single published benchmark number risks giving a false sense of precision. Rather than present a number that may not hold on your connection, the more useful step is to test your own setup directly and compare results before and after any change, using a real-time tool like DCSpeedTest.