NAT hides your entire home network behind a single IP address. It was supposed to be temporary. Three decades later, we've built the whole Internet around the workaround.
Your router blocks all uninvited traffic by default. Port forwarding creates specific exceptions—useful for game servers, remote access, and self-hosted services, but every exception is a door that doesn't check IDs.
CGNAT places your entire home network behind your ISP's NAT, not just your own router's. Your router thinks it has a public IP. It doesn't—and that breaks everything that depends on inbound connections.
Two routers, each doing exactly what it should, creating a dead end for any traffic trying to reach you. Here's how to make one step aside.
Two computers hiding behind routers, both using addresses that mean nothing on the Internet, somehow establish direct connections. This is the invisible negotiation that makes video calls, gaming, and peer-to-peer communication possible.
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