NAT (Network Address Translation) determines whether two players can establish a direct peer-to-peer connection for online play. The server matches players based on their NAT type to avoid failed connections.
Your router forwards traffic freely. You can connect with anyone. Best experience for online play.
Your router filters by IP address. You can connect with Open and Moderate players. Works well for most matches.
Your router uses symmetric NAT. Port numbers change with each connection, making hole-punching unreliable. You can only be matched with other Strict players, and even then the connection may fail.
| Open | Moderate | Strict | |
|---|---|---|---|
| Open | ✓ Works | ✓ Works | ✗ Blocked |
| Moderate | ✓ Works | ✓ Works | ✗ Blocked |
| Strict | ✗ Blocked | ✗ Blocked | ~ May fail |
Strict↔Strict matches are allowed by the server but peer-to-peer connection may still fail depending on each player's router configuration.
Steps vary by router model — search for "your router model UPnP" or "your router model port forwarding" for instructions.