Internet Connection Sharing and NAT Explained

NAT (Network Address Translation) allows multiple devices on a private network to share a single public IP address. The router performs NAT — it tracks outbound connections and routes returning traffic to the correct internal device. This is how virtually every home and business router works. The private IP ranges used internally (192.168.x.x, 10.x.x.x, 172.16-31.x.x) are not routable on the internet — they're only meaningful within your local network. The router presents a single public IP to the internet. When a server on the internet responds, the router's NAT table directs the response to the internal device that initiated the connection. NAT types: Full Cone (most permissive — any external host can send data once a mapping exists), Restricted Cone, Port Restricted Cone, and Symmetric (most restrictive — new mapping for each destination, problematic for peer-to-peer and some VoIP). For gaming or VoIP issues related to NAT, enabling UPnP (automatic port mapping) or configuring a DMZ for the affected device can resolve restrictive NAT problems. Double NAT (router behind router) is a common cause of connectivity issues — ensure only one device is performing NAT between the internet and your devices.