Diagnosing mobile data stops after a phone update
There are several common reasons why Three mobile data, calls or texts might stop working. These include an incorrect APN configuration, a temporary network outage in your area, a SIM card that needs re-seating, or a software issue on your device. This guide walks through each possible cause and the fix for each one.
Troubleshooting checklist
Working down this Three list in sequence normally resolves it quickly
Clearing network caches to restore data (Three Internet Problems Fix)
Before changing any settings, visit the Three APN hub or check a third-party site like Downdetector to confirm whether there is a known Three outage in your area. If the network is down, you simply need to wait for Three to restore service — no settings changes will help during an active outage.
Troubleshooting checklist
Following the Three sequence below typically sorts it early
Testing data with another SIM or network (Three Internet Problems Fix)
Pull down your notification shade and tap Aeroplane Mode to enable it. Wait ten seconds, then tap again to disable it. This forces your phone to drop its current connection and reconnect fresh to the Three mast. This fixes the majority of temporary signal and data issues.
Troubleshooting checklist
Three issues usually clear within the opening steps if taken in order
Last resort: factory reset network settings (Three Internet Problems Fix)
Hold the power button and select Restart. A full restart clears the modem cache and re-registers your SIM on the Three network. This fixes many data and signal issues that toggling aeroplane mode does not resolve.
Troubleshooting checklist
Taken in order, these Three steps normally resolve things fast
Step 4 — Re-seat the SIM on Three when internet is down
Switch the phone off entirely, then eject the SIM tray with the tool or a straightened paperclip. Take the SIM out, check the gold contacts for dirt or corrosion, wipe gently with a dry cloth if needed, then reinsert firmly and power back on.
Troubleshooting checklist
Most Three faults resolve early when the steps are followed in sequence
Step 5 — Check Three's APN settings when internet is down
| Setting | Value |
|---|---|
| APN Name | 3internet |
| Username | (leave blank) |
| Password | (leave blank) |
| MMSC | http://mms.um.three.co.uk:10021/mmsc |
| MMS Proxy | 193.113.200.195 |
| MMS Port | 8799 |
| Authentication Type | None |
| APN Type | default,supl,mms |
An incorrect APN is a common cause of mobile data not working even when you have signal. Go to Settings → Mobile Network → Access Point Names and verify the APN values match Three's recommended settings. Visit the Three APN hub for the correct values, or search this blog for the Three APN guide for your specific device.
Troubleshooting checklist
Go in order here — Three problems tend to clear near the top
Step 6 — Reset Three's network settings when internet is down
Android users: Settings → General Management → Reset → Reset Network Settings restores the default APN and clears Wi-Fi/Bluetooth, leaving apps and personal data untouched.
On iPhone: Go to Settings → General → Transfer or Reset iPhone → Reset → Reset Network Settings. Your iPhone will restart and reconnect to Three with default settings.
Troubleshooting checklist
Sequence matters: most Three cases resolve within a step or two
Step 7 — Contact Three support when internet is down
If none of the above steps resolve the issue, contact Three customer support. There may be a problem with your account, your SIM may need replacing, or there may be a localised network fault. Have your account number and phone IMEI ready (dial *#06# to find your IMEI). Visit the Three APN hub for contact details.
Troubleshooting checklist
These Three checks resolve most cases when done in order