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Mobile data vs Wi‑Fi: different public IP?

Yes. On Wi‑Fi you typically appear as your broadband ISP’s public IP. On cellular you appear as your mobile carrier’s IP from their pool—often a different city in geolocation databases too.

How to verify

  1. Open What Is My IP Address IP on Wi‑Fi and note IPv4 (and IPv6 if shown).
  2. Turn Wi‑Fi off, use mobile data, refresh the page.
  3. Compare—addresses and location lines usually change.

Carrier-grade NAT on LTE

Mobile operators often multiplex many subscribers behind fewer IPv4 addresses. Your “public” IP might be shared or rotate quickly—fine for browsing, sometimes awkward for apps that treat IP as identity.

Wi‑Fi stability

Home cable or fiber usually gives a more stable address for longer stretches, though still dynamic on many plans. Rebooting the modem can still rotate it—see why your IP changes.

Testing support tickets

State exactly which network you used when you copied the IP. If you toggled airplane mode, refresh after each state. For copy tips: copy IP for support.

People also ask

Does 5G vs LTE change the IP? It can, because the carrier may assign a new session when the radio tech switches.

Tethering from phone to laptop? The laptop often inherits the phone’s carrier NAT path—checkers usually align, but VPN on one device can differ.

Public Wi‑Fi vs home? Coffee shop Wi‑Fi shows the venue’s ISP and IP, not your home broadband.

Extended guide: testing methodology

To compare fairly, disable VPN on all devices, wait for full reconnect, then refresh the checker. Toggle airplane mode on cellular to force a new session when you need to see rotation behavior.

Remember geolocation on LTE may point to a regional hub—do not treat map pins as device GPS.

International roaming can assign addresses from partner networks; mention roaming when filing tickets about region locks.

Bandwidth and IP address are independent—fast LTE does not imply a “better” IP for authentication, only a different exit.

Family plans and tethering quirks

Some carriers NAT tethered laptop traffic differently from on-device browsing. If a site blocks “mobile” ranges, tethering might inherit that label even when the laptop browser looks like desktop Safari. Test both direct cellular and hotspot paths when diagnosing “works on phone, fails on laptop” cases.

5G vs LTE can shift anchor gateways; your public IP might change when the modem reattaches to a new node even without moving physically—note that when support asks “did anything change?” mid-session.

Wi‑Fi calling and SMS-over-IP do not replace your broadband path for general browsing; still use the checker over the transport you care about (Wi‑Fi vs cellular data).

Corporate SIMs with private APNs might show a carrier exit unlike consumer lines—coordinate with mobile IT before comparing readings to home broadband.

Fair comparisons on speed tests

Run speed tests on each interface separately—mixing results confuses “slow Wi‑Fi” with “slow LTE” when only one path is bad.

Disable download-heavy background apps before measuring; they steal airtime without changing your IP semantics.

International travelers: local roaming partners change both latency and visible ASN—note partner names in tickets.

Wi‑Fi assist features on phones may silently switch to cellular when Wi‑Fi is weak—your IP can jump without a visible toggle.

Metered connections: OS prompts might delay background sync; IP still changes independently of sync timing.

Finally, teach friends that “bars” indicate radio quality, not IP correctness—two concepts, two troubleshooting paths.

Simple rule

Changed the physical path? Expect a possible public IP change. Changed only websites while staying on the same path? The IP usually stays put until DHCP or carrier policies say otherwise.

Summary checklist

Step one: record Wi‑Fi results with VPN off. Step two: disable Wi‑Fi, enable cellular, wait for full bars, refresh the checker. Step three: note IPv4/IPv6 lines and approximate location text. Step four: paste into your ticket with timestamps. Step five: if behavior differs only on one path, say so explicitly—engineers need to know whether the bug is carrier-specific.

Family plans with tethering limits may throttle or deprioritize hotspot traffic; that affects performance tests but usually not the visible IP family. If you use a carrier VPN profile from work, test personal profile too.

When comparing “same phone, two networks,” rebooting the radio stack between tests reduces stale session artifacts. Document device model and OS version if support asks—radio firmware matters for IPv6 exposure.

Long term, save these steps as a personal runbook so you do not re-learn the sequence every time a site asks for “IP while on data.”

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