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Three Internet Not Working Fix Guide
Ordered by likelihood of being the real cause, these steps for Three's network start with outage and APN checks before hardware.
Three operates its own UK network and was historically known for strong 5G rollout in dense urban areas. Several MVNOs — including SMARTY, iD Mobile, RWG Mobile and spusu — run on Three's infrastructure. Three is also progressing a network-sharing arrangement with Vodafone under the VodafoneThree merger.
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Step 1: Check for Three Network Outage
Before changing any settings, check whether Three is experiencing a network outage in your area. An outage is the most common reason for sudden mobile data loss across an area.
Check Three status: https://www.three.co.uk/support/network-and-coverage/service-status
If there is a confirmed outage in your area, no settings changes will help — wait for Three to restore the network and check the status page for estimated recovery time. You can also check Downdetector for user-reported issues.
Step 2 — Quick Three Fixes to Try First
Work through these five checks in order — together they resolve the large majority of Three data faults without needing to touch APN settings at all.
- The fastest re-registration trick is a 30-second Aeroplane Mode toggle.
- Fully restarting clears cached data that a quick toggle sometimes doesn't touch.
- Double-check Mobile Data is enabled: Settings › Mobile Data (iPhone) or Settings › Connections › Mobile Data (Android).
- Look at your data balance in My3 — running out of allowance produces symptoms that look exactly like a network fault.
- Intermittent data often traces to a marginal SIM contact — power off and reseat the card.
Step 3: Verify Three APN Settings
An incorrect APN is a leading cause of data problems, especially following a factory reset, OS update, SIM swap, or a move from another network. Check and correct it if needed.
Correct Three APN: three.co.uk
How to check APN settings on Android
- Navigate to Settings › Connections › Mobile Networks › Access Point Names (Samsung) or Settings › Network & internet › Mobile network › Access point names (Pixel).
- Open the Three APN entry and confirm it reads exactly three.co.uk — watch for extra spaces.
- Check APN Type includes at minimum default and supl.
- If the entry is missing or wrong, the Three APN settings guide has the full set of values.
- Save, activate with the radio button, and restart.
How to check on iPhone
- Look at Settings › Mobile Data › Mobile Data Network, if shown.
- Confirm it displays three.co.uk.
- If greyed out, the carrier bundle manages it — check Settings › General › About for an update.
Step 4 — More Advanced Three Fixes
- Update your phone's OS if there's a pending update: Settings › System › Software Update — this occasionally resolves registration faults on its own.
- Check Settings › General › About on iPhone for a carrier update, and install it if offered.
- Reset network settings as a next step: Android — APN settings, ⋮ › Reset to Default. iPhone — Settings › General › Transfer or Reset iPhone › Reset › Reset Network Settings. This wipes saved Wi-Fi passwords too.
- Testing the SIM in a different phone isolates the handset as the cause if it works there.
- Test a different SIM in your phone — if that one connects fine, your Three SIM or account is the likely cause.
- Request a free SIM replacement from Three if the problem persists after all of the above.
- Call Three support on 333 (free from Three) or 0333 338 1001 for an account-level check — they can also confirm whether there's a known issue with your local mast.
Common Causes of Three Data Not Working
| Symptom | Likely Cause | Fix |
|---|---|---|
| Sudden data loss, was working before | Network outage or SIM registration issue | Check status page; toggle Aeroplane Mode |
| After factory reset / phone change | APN settings not transferred | Re-enter APN settings: three.co.uk |
| Data works then stops randomly | Poor signal, congestion, or SIM contact issue | Reseat SIM; check coverage map |
| Signal bars showing but no internet | Incorrect APN or data plan expired | Verify APN; check data balance in My3 |
| Very slow speeds (not outright broken) | Data throttling, network congestion | Check if data cap hit; try different time of day |
| Works on Wi-Fi but not mobile data | Mobile data toggle off or APN wrong | Enable mobile data in Settings; verify APN |
| After iOS/Android update | OS update overwrote network settings | Reset network settings and re-enter APN |
Frequently Asked Questions — Three Internet Not Working
How do I fix Three mobile data not working?
Begin with Aeroplane Mode — on for 30 seconds, then off — which re-registers your phone on the network and fixes many cases outright. If data is still down, check Settings › Mobile Networks › Access Point Names and confirm the APN is exactly three.co.uk. Also worth a quick check of https://www.three.co.uk/support/network-and-coverage/service-status for a known outage. If it's still not working after that, restart the phone and re-enter the APN from scratch.
What is the Three APN for mobile data?
That's three.co.uk. The Three APN settings guide has the rest of the fields too, in case you need to set up MMS or check the values on a second device.
Is Three down right now?
Start with https://www.three.co.uk/support/network-and-coverage/service-status for Three's official outage status. If it looks fine there but you're still having trouble, Downdetector sometimes picks up localised issues faster.
Why does Three show signal but no internet?
Seeing signal bars only tells you the phone has registered on the mast — it says nothing about whether data is actually flowing. Check: Mobile Data is on in Settings, APN matches three.co.uk exactly, you haven't exhausted your data allowance, and there's no outage in your area right now.
How do I reset Three APN settings?
Android users: open APN settings and tap ⋮ › Reset to Default. iPhone users: Settings › General › Transfer or Reset iPhone › Reset › Reset Network Settings — this wipes Wi-Fi passwords as a side effect, so have those handy. Re-enter three.co.uk afterwards.
Three data stopped working after a phone update — what do I do?
This is a common side effect of OS updates overwriting custom network settings. Go to Settings › Mobile Networks › Access Point Names and put three.co.uk back in. iPhone owners should also check Settings › General › About for a carrier update, then restart.