Address sharing.
WHAT IT DOES
Allows many devices to share one public address.
HOW
The router rewrites addresses and tracks which internal device made each request.
WHY IT EXISTS
There are not enough IPv4 addresses.
WHAT IT MEANS FOR YOU
Your devices are not directly reachable from outside, by default.
WHAT THAT AFFECTS
Running services at your premises Some applications requiring direct connections Identifying individual devices in external logs
THAT LAST POINT
External services see one address for your whole network.
WHAT THAT EXPLAINS
Why a rate limit or block affects everyone in an office at once.
And why a website may block your whole premises because of one device's behaviour.
WHAT TO DO ABOUT THAT
Identify which device, if a block occurs.
WHAT IPV6 CHANGES
Enough addresses for every device, removing the need for sharing.
Adoption is gradual.
WHAT TO CHECK
Your public address, when diagnosing anything external.
