Why does my IP address change? Public and private causes explained

The two IPs people confuse

Every internet-connected device you own actually carries two separate addresses, and they live in different worlds. The first is your private (LAN) address — something like 192.168.1.42 — which your router hands to each device inside your home so they can talk to each other and to the router. The second is your public (WAN) address, the single address your ISP assigns to your connection, which is the one the rest of the internet actually sees. Your router translates between the two using NAT. If you want the full breakdown of that split, see public vs private IP.

The reason this matters here is that either address can change, for reasons that have nothing to do with each other. When someone says “my IP keeps changing,” the right first question is: which one? The address a website reports for you is the public one — that's what what is my IP shows. The address you use to reach your router's admin page is the private one. They change independently, so we'll treat them separately.

Why the public IP changes

Your public address is leased to you by your ISP, and residential connections almost always get a dynamic IP rather than a fixed one. Several things can cause it to rotate:

DHCP leases from the ISP. Your ISP assigns your address for a fixed period — the DHCP lease — and your router renews it before it expires. Often you keep the same address across many renewals, but the ISP is under no obligation to give you the same one back, and when a lease is allowed to lapse you can be handed a different address from the pool. This is the everyday mechanism behind a “dynamic” IP; see how DHCP works for the full handshake.
Router reboot or reconnect. Powering your router off and on, or losing the line and reconnecting, forces a fresh DHCP request. Depending on how long you were offline, you may come back with the same address or a new one. This is why the classic “unplug it for a minute” trick sometimes changes your public IP and sometimes doesn't.
ISP re-addressing. ISPs periodically reorganize their address pools — moving customers between segments, retiring ranges, or rebalancing equipment. When that happens your address changes with no action on your part, and no warning.
CGNAT handing you a different shared address. If your ISP puts you behind carrier-grade NAT, the public address the internet sees isn't exclusively yours at all — it's shared with many other customers, and the ISP's NAT gear can move you onto a different shared egress address as it rebalances its pools, sometimes as often as daily.
Mobile networks hopping. On cellular data your public address is assigned by the carrier, and mobile networks are essentially all behind CGNAT. As your phone moves between towers and gateways, the public address attributed to you can change repeatedly within a single session.

Why the private IP changes

The address changing might not be the public one at all. Inside your home, your router runs its own DHCP server and leases private addresses to your devices, and those leases turn over for their own reasons:

Your router's DHCP lease to the device. Just like the ISP, your router hands out addresses for a limited time from a pool (commonly inside 192.168.x.x). If a device is off long enough for its lease to expire and the address gets reassigned, it may pick up a different one when it rejoins.
Reconnecting and device order. Which address a device lands on can depend on the order devices join the network. Boot your laptop before your phone one day and after it the next, and the two can swap addresses. Nothing is wrong — the pool is simply being handed out first-come, first-served.
MAC randomization. Modern phones and laptops often use a randomized Wi-Fi MAC address per network for privacy. Because the router keys its leases on MAC, a new random MAC can look like a brand-new device and get a brand-new private address, even on a network you've joined many times before.

If you need a device to keep the same private address — a printer, a NAS, a home server, anything you reach by its LAN address — the fix is a DHCP reservation (sometimes called a static lease). In your router's admin page you bind a specific address to the device's MAC, and from then on the router always leases that device the same address. It's cleaner than setting a static IP on the device itself, because the router still owns the whole scheme and won't hand the reserved address to anyone else.

IPv6 privacy extensions: changing on purpose

There's one case where your address changes by design rather than by accident. With IPv6, every device typically gets a globally routable address of its own, and privacy extensions (RFC 4941) deliberately generate temporary addresses that rotate — often daily — so that your device isn't trivially trackable across the web by a single, stable identifier. Your device keeps a stable address for incoming connections while sending outbound traffic from the rotating temporary one. So if you have IPv6 and notice your address shifting on a schedule, that's a privacy feature working as intended, not a fault. You can check whether your connection has working IPv6 with the IPv6 test or the IPv6 status page.

How to check and how to get a stable address

To see your current public address, open what is my IP or the home page. Check it, wait a while or reboot your router, and check again — that tells you empirically whether your public IP is actually moving. For a private address, look at your router's admin page or your device's network settings.

If you've confirmed the change is real and you need it to stop, there are two practical routes, covered in depth in static vs dynamic IP:

A static IP from your ISP. Many ISPs sell a fixed public address as an add-on. It's the most direct fix, and the right one if you genuinely need a permanent, unshared address — but note it's often unavailable if you're behind CGNAT.
Dynamic DNS (DDNS). Instead of pinning the address, you pin a name. A small client on your router watches for your public IP changing and updates a hostname to match, so a fixed name always resolves to wherever you are now. For most home users who just want to reach their network from outside, this is cheaper and easier than buying a static IP — as long as you're not behind CGNAT, which blocks inbound connections regardless of the name.

When a changing IP matters — and when it doesn't

Most of the time, a changing IP is completely invisible and harmless. Browsing, streaming, shopping, video calls, and online gaming all initiate their connections outward from your device, so it doesn't matter that today's address differs from yesterday's — the connection is established fresh each time.

It starts to matter in a few specific situations:

Self-hosting. If you run a game server, a home camera, a VPN server, or any service you reach from outside, a moving public IP means people (including you) can't find it reliably. This is the classic case for DDNS or a static IP.
IP allow-lists. Some workplaces, databases, and admin panels only accept connections from a known address. When your home IP rotates, you get locked out until the allow-list is updated — which is exactly why those setups expect a static IP.
Getting logged out or re-challenged. Some services treat a sudden change of IP as a sign of a hijacked session and log you out or ask you to re-authenticate. Annoying, but generally a security feature rather than a bug.

If none of those apply to you, a changing IP needs no action at all. It's the default, intended behavior of a residential connection — and often, as with IPv6 privacy extensions and CGNAT, a side effect of the systems that keep the modern internet running on a finite pool of addresses. The terms in the glossary fill in the rest.

Frequently asked questions

Is it bad that my IP address keeps changing?

For almost everyone, no. A changing public IP is the normal behavior of a residential dynamic connection, and it has no effect on browsing, streaming, gaming, or video calls, because those connections are all initiated outward from your device. A rotating address only becomes a problem when something needs to reach you at a fixed location — self-hosting a service, connecting to an IP allow-list at work, or a firewall rule pinned to your old address. In those cases you want a stable address rather than assuming the changing one is a fault.

How do I stop my IP address from changing?

It depends on which IP you mean. To keep your device's private LAN address fixed, set a DHCP reservation in your router so it always leases the same address to that device's MAC. To keep your public internet-facing address fixed, you generally need a static IP from your ISP (often a paid add-on) or, more practically, a dynamic DNS (DDNS) hostname that automatically follows your changing address so a name always points at you.

Why does my phone have a different IP everywhere I go?

A phone gets a fresh address every time it joins a different network. On Wi-Fi it receives a private address from that network's router by DHCP, so home, the office, and a coffee shop all give it different local addresses. On cellular data the mobile network assigns the public address, and because mobile networks are almost universally behind carrier-grade NAT, your public IP is shared and can rotate as the network moves you between gateways. Many phones also randomize their Wi-Fi MAC address per network, which can produce a new private address even on a network you have joined before.

Why does my IP address change?