Why Does My IP Change?

Dynamic vs static IP addresses

The most fundamental reason IP addresses change is the distinction between dynamic and static assignments:

• Dynamic IP — the address is assigned temporarily and can change. Most residential and mobile internet connections use dynamic IPs. This is the default for nearly all home broadband plans.
• Static IP — the address is permanently assigned and stays the same. Static IPs are typically used by businesses, servers, and anyone who needs a consistent, reachable address. They usually cost extra.

How DHCP works

DHCP (Dynamic Host Configuration Protocol) is the system responsible for automatically assigning IP addresses. When your device connects to a network — whether a home router, mobile network, or corporate LAN — it broadcasts a request for an address. A DHCP server responds with an available IP and a lease time: the period for which that address is yours.

When the lease expires, the address may be renewed (often with the same IP, if it is still available) or a different address may be assigned. This is why leaving your router off overnight, or reconnecting after a long absence, sometimes results in a different IP.

When your IP is likely to change

• Restarting your router — your modem releases its current DHCP lease and requests a new one. The ISP may assign a different address from its pool.
• Extended downtime — if your connection is offline for long enough that the DHCP lease expires, your ISP reclaims the address and may give it to someone else.
• ISP infrastructure changes — ISPs periodically reorganize their address pools. This can cause address changes even without any action on your part.
• Moving locations — connecting from a different physical location (hotel, café, mobile network) will always give you a different IP.
• Switching between IPv4 and IPv6 — these are entirely separate address spaces. Your IPv4 and IPv6 addresses are independent and may change at different times.

Mobile networks change IPs frequently

Mobile (cellular) network addresses are especially volatile. Carriers manage enormous pools of addresses shared across millions of devices. Your IP on a mobile network can change every few minutes, every time your device hands off between towers, or whenever you toggle airplane mode. Many mobile carriers also use Carrier-Grade NAT (CGNAT), meaning thousands of users share a single public IP simultaneously.

How to get a stable IP

• Request a static IP from your ISP — available on many business plans, sometimes for an extra fee on residential plans.
• Use a VPN with a dedicated IP — some VPN providers offer fixed IP addresses as an add-on, giving you a consistent egress address while still routing through the VPN.
• Dynamic DNS (DDNS) — if a static IP is not available, DDNS services can map a fixed hostname to your current dynamic IP, updating automatically whenever it changes. Useful for self-hosting.