Online NAT Type Checker

See how your network translates traffic with a quick WebRTC-based NAT probe, then learn why NAT type matters for gaming, VoIP, and peer-to-peer connections.

Quick WebRTC probe to infer your NAT behavior.

Uses public STUN servers; results are heuristic and can vary per network.

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Click the button to run a quick WebRTC-based NAT probe.

What is NAT?

Network Address Translation (NAT) lets multiple devices share a single public IP address by rewriting packet source and destination details as traffic crosses your router. It conserves IPv4 addresses and adds a light layer of isolation, but it also introduces translation rules that influence how inbound connections reach your device.

Modern routers usually run some flavor of NAT that opens return paths only after you send traffic out. This behavior keeps unsolicited traffic from reaching your devices, but can complicate direct peer-to-peer sessions that need predictable, open ports.

How does NAT type influence your connection?

Open or Full Cone NAT

Easiest for peer-to-peer. Ports stay consistent and return traffic flows freely once opened. Best for online gaming lobbies, VoIP, and direct file sharing.

Moderate / Restricted NAT

Ports are translated but allow replies that match your outbound mapping. Most home networks fall here, and most apps work with some STUN/TURN assistance.

Strict / Symmetric NAT

Every destination can get a unique port mapping, making hole-punching unreliable. Peer-to-peer and some multiplayer games may fail unless a relay (TURN) server is used.

Blocked or Unknown

Firewalls or carrier-grade NAT can block UDP discovery entirely. You may need a VPN, port forwarding, or a relay service to enable direct connectivity.

Tips to improve NAT friendliness

  • Use wired or primary routers instead of double-NAT guest/mesh nodes when possible.
  • Enable UPnP or add manual port-forward rules for the apps or games you trust.
  • Check for ISP carrier-grade NAT; a static IP or VPN with port forwarding can help.
  • Ensure your firewall allows outbound UDP so STUN/TURN discovery can work.