Most broadband customers never think about IP addresses. They plug in their router, connect their devices, and expect everything to work.
However, if you've ever struggled with port forwarding, remote access, self-hosted services, or certain online applications, there's a good chance you've encountered a technology called CGNAT.
Many internet providers now use it by default, often without customers realising.
So what exactly is CGNAT, and why does it matter?
What Is CGNAT?
CGNAT stands for Carrier Grade Network Address Translation.
To understand it, we first need to talk about IPv4 addresses.
Every device connected to the internet needs an address. Historically, this was provided through IPv4, which uses a pool of approximately 4.3 billion unique addresses.
That might sound like a lot, but with billions of people, smartphones, computers, servers, and IoT devices online, those addresses have largely been exhausted.
As a result, many providers now share a single public IPv4 address between multiple customers using CGNAT.
Instead of your router receiving its own public address, it receives a private address, and the ISP translates your traffic behind a shared public IP.
Why Do Providers Use CGNAT?
The answer is simple: IPv4 addresses are expensive.
As address availability has declined, the market value of IPv4 space has increased significantly.
Using CGNAT allows providers to serve many customers while using fewer public IPv4 addresses.
For some providers, this reduces costs and simplifies growth.
For customers, the experience is often mixed.
What Problems Can CGNAT Cause?
For basic web browsing, streaming, social media, and video calls, CGNAT usually works perfectly fine.
The problems appear when you want inbound connections from the internet.
Port Forwarding Doesn't Work
Port forwarding allows external devices to connect to services running on your network.
Common examples include:
- Game servers
- CCTV systems
- Home automation platforms
- Self-hosted websites
- Remote desktop access
- VPN servers
With CGNAT, you typically cannot create working port forwards because the public IP address isn't actually assigned to your connection.
Remote Access Becomes More Complicated
Many homelab enthusiasts use services such as:
- WireGuard
- OpenVPN
- Home Assistant
- Plex
- Nextcloud
These can require additional workarounds when operating behind CGNAT.
Shared Reputation
When dozens or even hundreds of customers share a single public IP address, the actions of one user can potentially affect others.
This is uncommon, but shared IP reputation can occasionally cause issues with certain services or security systems.
Troubleshooting Is Harder
When multiple customers appear under the same public IP, diagnosing network issues can become more complex for both customers and support teams.
Does CGNAT Affect Gaming?
This is one of the most common questions.
For most modern games, CGNAT has little or no impact on latency.
Your ping is primarily determined by routing and network quality rather than whether you're behind CGNAT.
However, some games and peer-to-peer applications may report stricter NAT types, which can occasionally affect hosting sessions or direct connections.
The Long-Term Solution: IPv6
The internet's long-term answer to IPv4 exhaustion is IPv6.
IPv6 provides a vastly larger address space, allowing every device to have its own globally routable address.
With proper IPv6 deployment, the need for technologies like CGNAT is significantly reduced.
Unfortunately, not every service fully supports IPv6 yet, which means public IPv4 addresses still remain important today.
How To Tell If You're Behind CGNAT
One simple check is to compare:
- The WAN IP address shown in your router.
- The public IP address reported by websites such as "What Is My IP".
If the addresses don't match, there's a good chance you're behind CGNAT.
Another indicator is if your router receives an address from private ranges such as:
- 10.0.0.0/8
- 172.16.0.0/12
- 192.168.0.0/16
- 100.64.0.0/10
The 100.64.0.0/10 range is commonly used specifically for CGNAT deployments.
Olilo's Approach
At Olilo, we believe customers should have full control over their internet connection.
That's why every prosumer broadband service includes:
- A public IPv4 address
- Native IPv6 connectivity
- No CGNAT
- Support from people who understand networking
Whether you're running a homelab, accessing services remotely, hosting applications, or simply want a more traditional internet connection, you won't find your traffic hidden behind carrier-grade NAT.
Final Thoughts
CGNAT isn't inherently bad. It allows providers to continue growing despite IPv4 shortages and works perfectly well for many everyday internet activities.
However, if you value control, remote access, self-hosting, or advanced networking features, it's worth understanding whether your provider uses it.
Sometimes the difference between something working immediately and spending hours troubleshooting comes down to whether you have your own public IP address.
