CGNAT or DS-Lite: Port Forwarding Fails
Tags: networking, cgnat, hosting, troubleshooting
If your ISP uses CGNAT or DS-Lite, port forwarding will not work and inbound IPv4 connections will fail.
How to detect CGNAT
- Compare your router WAN IP to a public IP checker.
- If they differ, you are likely behind CGNAT.
- Carrier-grade ranges include 100.64.0.0/10.
Fix options
- Request a public IPv4 address from your ISP.
- Use a hosted server instead of home hosting.
- Ask the ISP about native IPv4 or a static IP plan.
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