What is CGNAT?

CGNAT, short for carrier-grade NAT, is how many internet providers share one public IPv4 address among many customers. There aren't enough IPv4 addresses for everyone, so providers, and nearly all mobile networks, use it to stretch the ones they have.

How it works

At home, your router already shares one public address among all your devices, a process called NAT (see public vs private IP addresses). With CGNAT, your provider adds a second layer. Your router gets a private address from the provider, and the provider's equipment shares one public address among many homes.

Signs you're behind CGNAT

• Port forwarding doesn't work, even when it's set up correctly, and our port checker says the port is closed.
• Your game console reports a strict or moderate NAT type, and hosting multiplayer games fails.
• Remote access to your cameras, storage drives, or remote desktop doesn't work from outside your home.

How to check

1. Sign in to your router (see how to log in to your router) and find the internet or WAN IP address on its status page.
2. Compare it with your public IP address on our homepage.
3. If they're different, you're behind CGNAT or a second router. An address from 100.64.0.0 to 100.127.255.255 is a strong sign of CGNAT, because that range is set aside for it. An address starting with 10., 172.16 to 172.31, or 192.168. means either CGNAT or a second router in your home.

What you can do

• Ask your provider for a public IPv4 address. Some providers give one free on request; others charge for it, often as a static IP add-on.
• Use IPv6. IPv6 has enough addresses that providers don't need CGNAT for it. If your connection has IPv6 (check what is my IPv6 address), your devices can be reachable over IPv6, provided your router's firewall allows it.
• Use a tunnel or mesh VPN service that connects outward from your home. Nothing needs to come in, so it works behind CGNAT for reaching your own devices.
• For gaming, UPnP can't fix CGNAT, because the limit sits with your provider. Ask the provider for a public address, or check whether the game can use relay servers. Our NAT type test shows what games are likely to see.
• If it's a second router at home (double NAT), put the provider's box in bridge mode, or forward the ports on both devices.

Is CGNAT bad?

For browsing, streaming, and video calls, you won't notice it. It only matters when something on the internet needs to reach a device in your home. Sharing an address can also mean extra CAPTCHAs now and then, because websites see many people behind one IP.