What Is Carrier-Grade NAT?
Carrier-Grade NAT (CGNAT) is a network address translation technology used by Internet Service Providers (ISPs) to reduce the consumption of public IPv4 addresses. As the pool of IPv4 addresses is nearly exhausted, many ISPs assign a single public IP address to multiple subscribers.
Instead of assigning a unique public IP to each customer device (such as an LTE/5G router), the ISP uses NAT at the carrier network level. As a result, your router may be behind a NAT inside the ISP’s network, making inbound connections from the internet (WAN) impossible without special configuration.
Why This Causes Problems with Remote Access and Port Forwarding
When setting up remote access (e.g., Web GUI, VPN, cameras, servers, SSH, etc.), CGNAT prevents devices on the internet from initiating direct connections to your router because:
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Your device does not have its own public IP address.
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The ISP does not forward incoming traffic to your device.
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Port forwarding doesn’t work, because you don’t control the public-facing IP.
How to Check If You're Behind CGNAT
Follow these steps to check:
1. Access Your Router’s Web Interface
Log into your router’s Web GUI by typing the local IP (e.g., 192.168.1.1) into your browser.
2. Locate the WAN IP Address
Go to the Network > WAN Status section (or similar) to find the WAN IP assigned to your router.
3. Use an Online Tool to Check Public IP
Visit a website like https://whatsmyip.com to see your current public IP address.
4. Compare the IP Addresses
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If the WAN IP and the public IP match, then CGNAT is not in use, and remote access should be possible.
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If the addresses are different (e.g., WAN IP starts with
10.x.x.x,100.64.x.x,192.168.x.x, or172.16–31.x.x) Your router is behind Carrier-Grade NAT, and remote access from outside will not work.
Example:
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WAN IP =
10.204.58.202 -
Public IP =
93.159.x.x
This indicates that CGNAT is active — and remote access will not be possible without changes by your ISP.
What to Do If You're Behind CGNAT
If you determine your LTE/5G router is behind CGNAT and you require remote access (for management, IP cameras, VPN, etc.):
Solution: Request a Public IP from Your ISP
Contact your mobile or internet service provider and:
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Ask for a dedicated public IPv4 address for your SIM card or LTE/5G router.
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Inquire if static IP allocation or DMZ/VPN configuration is available.
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Confirm any costs — many ISPs offer this as a paid service, but often at a reasonable rate.
Bonus: CGNAT and IPv6
Some ISPs now offer IPv6, which eliminates the need for NAT altogether. In this case, CGNAT can be bypassed. However:
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Your router and network must support IPv6.
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Remote access over IPv6 may require additional configuration (firewall rules, routing, filters).
Conclusion
CGNAT is a widespread workaround for IPv4 exhaustion, but it hinders remote access and port forwarding. If you suspect you're behind CGNAT:
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Check and compare your WAN and public IP.
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Confirm whether CGNAT is in place.
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Contact your ISP to obtain a public IP address.
Doing so will restore full remote access functionality and allow your device to be reachable from the outside world.