Do games and calls connect the quick way?
Strict NAT, a slow or broken IPv6 path and blocked UDP don't show up in a speed test, but each one pushes games and calls onto relays or slower paths. This checks all three from your browser.
Connection check
Takes about ten seconds. Turn off any VPN first, or it tests the VPN instead of your line.
All fine and still lagging? Check your game server distance and route or run the Lag Check.
How it works
Three checks run from your browser. The NAT check asks public STUN servers how your connection looks from outside, which shows whether games and calls can connect directly or need a relay. The IPv6 check times the same request over IPv6 and IPv4, because apps prefer IPv6 when it works even if it's slower. The last check sees whether your connection uses HTTP/3, which runs over UDP; if it can't, UDP may be blocked, and many games and calls rely on it.
Reading your result
- NAT open
- Games and calls can connect directly to other players. Nothing to fix.
- NAT strict
- Direct connections often fail, so matchmaking takes longer and voice may go through relays. Turn on UPnP on the router, or forward the game's ports.
- IPv6 slower than IPv4
- Apps take the slower path. Tell your provider, and as a test turn IPv6 off in the router and run the Lag Check again.
- UDP seems blocked
- Usually a firewall, a work or school network, or a VPN. Games and calls then fall back to slower paths.
Questions
How do I fix Strict NAT?
Turn on UPnP in the router, or forward the ports the game lists. The per-game guides have the ports, and the port checker shows whether a forward works.
Should I turn off IPv6 for gaming?
Only if this check shows IPv6 is clearly slower than IPv4. When both work at similar speed, leaving IPv6 on is better: games can connect directly over it.