Changing connections
Why does my IP address change?
Your IP address can change when you change networks, use a different VPN exit or receive a new address assignment. Before looking for a cause, establish whether the changing value is your device's local address, public IPv4 or public IPv6. They can change independently.
| What changed? | Possible explanation | Useful comparison |
|---|---|---|
| Wi-Fi to mobile data | You moved to a different provider network. | Record the connection type and the public address family. |
| Public IPv4 after a reconnect | The provider may have assigned a different address. | Compare before and after on the same network, without changing other factors. |
| Only the device's local IPv4 | A local DHCP assignment or network setting changed. | Check device settings and the router's client list. |
| Public address with a VPN | This request may use a different exit. | Record VPN state and selected exit, not just the country shown by a lookup. |
| IPv6 while staying connected | A temporary device address or the network prefix may have changed. | Compare the full address and the network conditions. |
Static vs dynamic IP addresses
A static assignment is intended to remain fixed under an arrangement with the network operator. A dynamic assignment can change, but it may also stay the same for a long time. Two equal observations, or even months without a change, do not prove that your provider guarantees a static address.
Setting a fixed private address on your laptop does not make your public address static. Likewise, a reservation in your home router concerns its local network. Ask your provider about public addressing if you need a predictable incoming connection.
Why IPv6 may change more often
A device can use temporary IPv6 addresses for outgoing connections. These are designed to change over time, as described in RFC 8981. The provider can also change the network prefix. An IPv6 change alone is not evidence of an outage or compromise.
Record a useful before-and-after
- Open Check my IP and record the time, public address and address family.
- Note Wi-Fi, Ethernet or mobile data, plus VPN/proxy state. Keep the same browser for the comparison.
- After the change you are investigating, repeat the observation. The connection test lets you compare IPv4 with IPv4 and IPv6 with IPv6.
- If support needs the results, share only the relevant observations through its support channel. A public forum does not need your full IP history.
Changing addresses can affect IP allowlists or incoming access. If your public IPv4 is shared through CGNAT, a static local address or dynamic DNS will not, by itself, provide an upstream port mapping. If your concern is only a new map location, read why IP location can be wrong.