# Why Is My Mobile Data Not Working?

> Mobile data fails in a handful of distinct ways, and the symptom narrows it down fast. What each one means, grouped by line, settings or place.

Phones and networks · Published 2023-06-03 · Updated 2026-08-21 · 5 min read

Page: https://esimradar.com/blog/data-not-working

![A man standing on a city street looking at his phone, apparently lost.](https://esimradar.com/blog-images/data-not-working/hero-3800149-1280.webp)

*The failure has a running order: roaming, then the data switch, then the APN, then the line itself. Guessing skips the one that is actually wrong.*

Mobile data does not fail in one way. It fails in about five, and what the phone is showing you narrows it down before you change a single setting. "No Service" and "full bars but nothing loads" are different problems with different causes, and treating them the same is how people end up resetting a phone that was one toggle away from working.

This page is the diagnosis. If you would rather just work through the repairs in order, [the fix sequence](https://esimradar.com/blog/fix-mobile-data-not-working) does that instead.

## Start with what the phone is showing

Match the symptom, and you have usually halved the search:

- No Service, or no bars at all — the line is not registered on any network. This is a registration problem, not a data problem.
- Full bars, nothing loads — the line is registered and the network is refusing the data session. Almost always a setting.
- Works on wifi, not on cellular — mobile data is off for that line, or the other line is carrying it.
- Some apps work, others do not — a per-app restriction, low data mode, or a VPN, not the connection.
- Connected but very slow — usually an allowance spent and the plan throttled rather than anything broken.

> **Note:** With two lines in one phone, the overwhelming majority of "no data" cases are one of exactly two settings: data roaming off for the travel line, or the wrong line selected to carry data. Check both before considering anything else on this page.

## Causes that are about the line

Nothing you change on the phone will help with these — the account or the hardware is the constraint.

- The phone is carrier-locked. It accepts the profile and then never registers, which reads as a broken plan — [Apple’s invalid SIM and no SIM checklist](https://support.apple.com/en-us/108914) opens with exactly this, and with where the phone reports it. [Ten seconds to check](https://esimradar.com/blog/iphone-unlocked).
- The plan expired, or the allowance is spent. Providers usually cut data rather than warning first.
- The profile was never activated — bought and installed but never connected, on a plan that needed a manual start.
- The account is suspended, most often over an unpaid bill or a payment flagged after purchase.

## Causes that are about settings

These are the common ones, and all are reversible in under a minute:

- Data roaming is off for the travel line. A travel eSIM always needs it on — [on for one line, off for the other](https://esimradar.com/blog/turn-on-off-roaming). The toggle lives under Cellular Data Options, which [Apple’s guide to the cellular data settings](https://support.apple.com/guide/iphone/view-or-change-cellular-data-settings-iph3dd5f213/ios) walks through.
- The wrong line is set to carry cellular data. Two lines, one data setting, and the phone will not guess.
- Low data mode or a data saver is throttling background traffic, which looks like some apps working and others not.
- A VPN is connected but its server is unreachable, so traffic goes nowhere while the phone reports a fine connection.
- The APN is wrong or missing. Genuinely rare, and worth [ruling the others out first](https://esimradar.com/blog/apn-settings).

## Causes that are about where you are

On Android the same settings carry different names, and [Google’s Pixel guide to fixing mobile connectivity](https://support.google.com/pixelphone/answer/14116080) maps them screen by screen. But sometimes nothing is wrong with the phone or the plan at all:

- No coverage. Rural areas, basements, tunnels and thick stone all do it, and a travel plan roams onto one specific local network that may not be the strongest one there.
- Automatic network selection settling on an operator your plan has no agreement with. Selecting manually fixes this and is worth trying early.
- Congestion — a stadium, a festival, an airport at peak. The line works and nothing moves.
- Band mismatch, on an imported phone missing the local frequencies. Uncommon, but it produces a stubborn partial signal.

## If it is a travel plan that never worked

A plan that has never connected once is usually roaming, the data-line setting, or a carrier lock — in that order. A plan that worked and stopped is usually the allowance. Neither is a reason to buy a second plan before checking. Compare on [price per GB](https://esimradar.com/faq) by [destination](https://esimradar.com/country) when you do buy.

## Common questions

### Why do I have full signal but no internet?

The line is registered and the data session is being refused. On a travel eSIM that is nearly always data roaming being off, or the other line being set to carry data.

### Why does my data work on one phone but not another?

Usually a carrier lock or a market variant lacking the local bands. Both are properties of the handset, not the plan.

### My data is connected but extremely slow. Is it broken?

Probably not. Most plans throttle rather than cut off once the allowance is spent, and congestion produces the same feel in crowded places.

### Should I reset my phone to fix mobile data?

No — that is far too large a step for what is nearly always a per-line setting. Work through the settings causes first.

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