Toolkit
NAT Type Check
This page does not fake a browser-based NAT type test. Instead, it gives you a practical way to understand open, moderate, and strict NAT and connect that back to CGNAT, double NAT, UPnP, and port forwarding.
What NAT type means in plain English
NAT type is a simplified way of describing how easy it is for outside connections to reach you. Games, hosting tools, and remote access apps often collapse a complicated network path into labels like open, moderate, or strict.
Those labels are useful, but they do not tell you exactly where the problem is. A strict NAT result might come from CGNAT, a second router, missing forwards, local firewall rules, or a mix of several issues.
Open NAT
Your network is usually able to accept inbound or peer connections with fewer obstacles. That does not guarantee every port is open, but it is the least restrictive state.
Moderate NAT
Some connections work, but peer-to-peer sessions or hosting can still fail depending on the other side, the game or app, and the router setup.
Strict NAT
Inbound or peer connections are heavily limited. CGNAT, double NAT, missing forwards, or firewall filtering are common reasons.
Related factor
CGNAT
If your ISP shares a public IPv4 address across many customers, open NAT and inbound hosting can be much harder or impossible on standard IPv4.
Related factor
Double NAT
An ISP gateway in front of your own router can create two NAT layers, which often causes moderate or strict NAT symptoms.
Related factor
UPnP
UPnP can automatically open ports on some routers, but it cannot override ISP-level CGNAT or another upstream NAT layer.
Related factor
Port forwarding
Manual forwards can help if you have a public IPv4 and the rest of the path is clean, but they do not fix CGNAT by themselves.
What to check next
A practical decision path
- Check the router WAN IP and compare it with your public IP using the CGNAT Checker.
- Look for double NAT if you have both an ISP gateway and your own router.
- Confirm the game, console, or app actually documents which ports or protocols it needs.
- Review UPnP, manual port forwards, and local firewall rules together instead of changing them one by one at random.
- If you suspect ISP-level NAT, ask whether your plan can receive a public IPv4 or whether a different product tier changes the answer.
Related toolkit pages
Keep narrowing down the cause
Tool
CGNAT Checker
Compare your WAN IP and public IP.
Open toolTool
Port Checker
See whether a TCP port appears reachable.
Open toolGuide
Why port forwarding fails
Review the most common inbound connectivity blockers.
Read moreSupport
FAQ
See practical answers about NAT type, WAN IP mismatches, and forwarding.
Read moreGuide
Router guides
Find your WAN IP and key router settings faster.
Read moreGuide
ISP pages
See cautious guidance for provider-specific troubleshooting.
Read moreInformational only: NAT type labels are shorthand. They can point you in the right direction, but they do not replace checking the router WAN IP, public IP, forwarding rules, and ISP setup directly.