What is CGNAT? Why your IPv4 address is shared on NBN.
If you've looked up your IP address and it starts with 100.64 to 100.127, or you can't host anything accessible from the internet, you're behind CGNAT — Carrier-Grade NAT. Your ISP is sharing a pool of public IPv4 addresses across many customers at once.
Tired of fighting your ISP? HIT Pacific — transparent pricing, no lock-in, real local support.
See our plansWhy this happens
- IPv4 addresses ran out globally in 2011 — ISPs must share the ones they have
- Australian ISPs have been slow to deploy IPv6, so CGNAT is used as a long-term stopgap
- CGNAT only applies to IPv4 traffic — IPv6 traffic is never subject to CGNAT
- With native IPv6, the large majority of internet traffic bypasses CGNAT entirely
How to fix it — step by step
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1. Check whether you're behind CGNAT
Search 'what is my IP address' in Google. Then check the WAN gateway shown in your router admin panel. If the router's WAN gateway is in the 100.64–100.127 range, you're behind CGNAT. You can also try setting up any inbound connection — if nothing from the internet can reach your home network, CGNAT is almost certainly why.
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2. Understand what CGNAT actually affects
Normal web browsing, video streaming, social media, email, and outbound video calls all work perfectly through CGNAT. What breaks: hosting anything accessible from outside (a web server, game server, NAS, camera), certain gaming lobbies and peer-to-peer applications, and any inbound connection. CGNAT is not a speed issue.
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3. Understand that IPv6 is the real answer to CGNAT
CGNAT exists because there aren't enough IPv4 addresses to go around. The structural fix is IPv6 — which has effectively unlimited address space and never requires NAT. With native IPv6, the large majority of your internet traffic doesn't touch IPv4 at all, making CGNAT irrelevant for those connections. HIT Pacific delivers native IPv6 on every plan; over 80% of traffic at our own HQ connection runs over IPv6.
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4. For the IPv4-only remainder
A small and shrinking fraction of internet services still only support IPv4. Technologies like 464XLAT handle this transparently — your device sends IPv4 traffic, the network translates it to IPv6, and reaches the IPv4-only destination on the other side. No action required on your part. This is the direction the internet is moving.
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5. Choose an ISP that provides native IPv6
CGNAT is a symptom of an ISP not having deployed IPv6. The most effective long-term fix is switching to an ISP that includes native IPv6 on every plan. As IPv6 adoption grows, CGNAT's relevance naturally shrinks.
Still having trouble?
If none of these steps resolve the problem, it may be an issue with your current provider. HIT Pacific offers transparent pricing, faster fault response, and local support.
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