What this test can see
A console prints NAT Type 1, 2 or 3 after probing its own connection. A browser cannot read that value, and a site that claims to show your console's NAT type is guessing. What a browser can do is build a real peer connection and check which kind of path worked. That uses ICE, the same method games use to connect you to other players. The three results map closely to the console labels:
Your device is reachable at a public address (a host candidate). Roughly the console's Type 1. Nothing to fix.
Your router does NAT, but a direct path worked (a server-reflexive candidate). Roughly Type 2, the most common result, and fine for almost every game.
No direct path; the connection only worked through a relay server. Roughly Type 3. This one causes matchmaking and party problems.
Why strict NAT is usually your provider
The most common cause is CGNAT (carrier-grade NAT). Many providers no longer give each customer a public IPv4 address; customers share one, and the provider's equipment translates the traffic. Your router is then not the last NAT on the path, and no setting in it can change that. Mobile internet is almost always CGNAT; on cable and fibre it depends on the provider and tariff.
Two ways to check:
- Compare addresses. If your router's WAN address is in
100.64.x.x–100.127.x.x (or 10.x, 172.16–31.x, 192.168.x) and differs from the IP shown in the box above, your provider adds a second NAT.
- Port forwarding has no effect. If a correctly set rule still leaves the port unreachable from outside, you are behind CGNAT.
How to fix a strict NAT
- Ask your provider for a public IPv4 address. The only fix for CGNAT. Many providers give one free on request. Ask for "public IPv4" or "no CGNAT"; a static IP is a different, usually more expensive product.
- Enable UPnP or NAT-PMP in your router, if you are not behind CGNAT. Games can then open their own ports.
- Forward the ports your game lists, if you prefer not to use UPnP.
- Turn on IPv6 if your provider offers it. IPv6 has no NAT, and many games use it when available.
- Remove a second router. A provider box plus your own router means two layers of NAT. Put the provider box in bridge or modem mode.
What NAT type does not explain
A strict NAT affects who can reach you: joining parties, hosting, peer-to-peer matches. It does not cause packet loss or an unstable ping to a game server. A relayed path can add some latency because the traffic takes a detour, but if your line drops packets or your ping jumps, the cause is elsewhere. The chart above shows that.
If your network blocks UDP completely (some company networks, VPNs, hotel or campus Wi-Fi), the test falls back to TCP and the NAT line says "UDP blocked" instead of a type.
Frequently Asked Questions
Can a website really tell me my NAT type?
Not the number your console prints; no browser can read that. It can build a real peer connection and report which path worked: direct, behind NAT or relayed. That is the same mechanism a game uses, so the answer matches what matters for matchmaking.
What is CGNAT?
Carrier-grade NAT: your provider shares one public IPv4 address between many customers. Your router cannot open ports for you then. Ask your provider for a public IPv4 address.
Does a strict NAT cause packet loss or high ping?
No. It does not drop packets and does not add latency to a game server, apart from a small detour on a relayed path. Packet loss and ping jumps have other causes; the chart on this page shows them.
How do I get an open NAT?
Without CGNAT: enable UPnP or forward your game ports, and avoid two routers in a row. With CGNAT: ask your provider for a public IPv4 address, or use IPv6 if it is available.
Why does the test say "UDP blocked"?
Your network blocks UDP, for example a company firewall, a VPN or hotel Wi-Fi. The test then measures over TCP, which establishes no NAT type and hides packet loss by resending lost packets.