Why is my mobile data not working when I have signal?
Signal bars measure the connection to the mast; data is a separate thing layered on top. Work through the switches, the allowance, the per-app restrictions, then the network configuration.
- Difficulty
- beginner
- Time
- 25 min
- Read
- 5 min
Short answer
Check the obvious switches first — mobile data on, data roaming on if you are abroad, aeroplane mode off, and the right line selected for data if you have dual SIM. Then check whether you have run out of allowance or hit a data cap you set yourself. Then check whether the app is restricted from using mobile data. If everything looks right, toggle aeroplane mode on and off to force a fresh registration, and if that fails, reset network settings.
Full bars with no data is confusing because the bars only tell you the phone can hear the mast. Data needs the phone to be registered for a data session, with a valid access point configuration, an allowance that has not run out, and permission at the app and system level. Any of those can fail with the bars unchanged.
Step by step
- Check the switches in the quick settings.Mobile data on, aeroplane mode off, and — if you are outside the UK — data roaming on. Data roaming being off is the correct default and the most common cause of no data abroad. Someone may also have set a data limit that has been reached and switched data off automatically.
- On a dual SIM phone, check which line data is assigned to.Only one line carries data at a time. If data is assigned to the line with no allowance left, or to a travel eSIM you have finished with, everything will look connected and nothing will load. This catches a lot of people after a holiday.
- Check the allowance and the bill.Log into the network's app or website over wi-fi. An exhausted allowance, an unpaid bill, or a bar applied to the account produces exactly this symptom. Networks also sometimes bar data specifically while leaving calls and texts working.
- Toggle aeroplane mode for fifteen seconds.This forces the phone to detach and re-register with the network, which resolves a stuck data session — the single most common transient cause. Do it before anything more drastic. A full restart achieves the same thing and also clears other stuck state.
- Check per-app restrictions.Both platforms let you block individual apps from using mobile data, and Android's data-saver mode restricts background data for everything not on an exemption list. If one app has no internet while others do, this is almost always why.
- Check the access point settings if you changed network or SIM.The access point name is the configuration that tells the phone how to reach the network's data service. It normally arrives automatically, but after moving networks, using a SIM from a smaller provider, or resetting the phone, it can be missing or wrong. Networks publish the correct values and there is usually an option to reset them to default.
- Reset network settings.This clears saved wi-fi passwords, Bluetooth pairings and mobile configuration and rebuilds them. It resolves a large share of stubborn data problems. Have your wi-fi passwords to hand before doing it, because you will be reconnecting everything.
- Test the SIM elsewhere and another SIM in your phone.Put your SIM in another phone; put another SIM in yours. Two minutes and it separates a phone fault from a SIM or account fault definitively. If your SIM fails in both phones, ask the network for a replacement — SIMs do wear out and the contacts corrode.
- Check for a network outage before assuming it is you.Networks publish status pages and outage checkers by postcode. If a mast is down, everything above is wasted effort. Ask someone nearby on the same network whether their data works.
If it doesn't work
Data works on wi-fi but not on mobile, and only for one app
Cause: That app is blocked from mobile data, or restricted by data saver — Fix: Find the app's data settings on iOS, or its mobile-data and unrestricted-data-usage settings on Android, and allow it. Background restriction settings are separate from foreground ones on Android.
Data stopped after travelling abroad and has not come back
Cause: Data roaming left off, or the data line still assigned to a travel eSIM — Fix: Check the roaming switch and, on dual SIM, which line is set for data. Also confirm the travel eSIM has been removed or disabled rather than left active.
Very slow rather than absent
Cause: Allowance exhausted and the network has throttled you, or a congested mast — Fix: Check the allowance in the network's app. Throttled data is a deliberate speed cap and no phone setting will change it. Congestion resolves on its own.
No data since a phone update
Cause: Network configuration changed or an access point setting was lost — Fix: Reset network settings, then check the carrier settings update prompt — both platforms distribute small network configuration updates separately from OS updates, and one may be pending.
No data and no calls, phone shows searching or emergency only
Cause: The SIM has failed, been deactivated, or the phone has lost registration — Fix: This is not a data problem. Restart, then test the SIM in another phone, then contact the network. A SIM that has been swapped or reissued deactivates the old one immediately.
Questions people ask
Why do I have five bars and no internet?
Bars show the radio signal strength to the mast, which is only the first requirement. A registered data session, a valid configuration, an allowance and a working backhaul from the mast all come after it. Strong bars with no data usually means one of those, not the radio.
Would a new SIM help?
Sometimes. SIM contacts corrode and old SIMs occasionally fail on newer networks. A replacement SIM is free from most networks and is a reasonable step once you have exhausted the settings, particularly if the SIM is many years old.
Should I turn off 5G?
In an area with patchy 5G coverage, a phone that keeps switching between networks can behave poorly. Setting the preferred network type to 4G is a legitimate test and often improves battery life too. It is a diagnostic worth trying rather than a permanent recommendation.
Does a VPN cause this?
It can. A VPN that has failed to connect leaves the phone with an apparently working data connection and nothing loading. Turn any VPN off as an early step — it is a very common and very confusing cause.