How to Fix Mobile Data Not Working on Your Phone

Published 2026-10-16 · Marion Phone Repair

Your phone has signal bars but mobile data does not work. Web pages do not load, apps show connection errors, and the data indicator (4G, LTE, 5G) is missing or shows an exclamation mark. Calls and texts may work fine because they use the voice network, but anything requiring an internet connection fails. Mobile data problems are usually caused by incorrect settings, carrier provisioning issues, or network configuration errors that are fixable without repair.

Basic checks

Mobile data is turned on

This sounds obvious but it is the most common cause. Mobile data can be turned off accidentally from the quick settings panel:

Android: Pull down the notification shade and check that the Mobile Data tile is enabled (highlighted). Or go to Settings, Network and Internet, Mobile Network, and toggle Mobile Data on
iPhone: Settings, Cellular, and make sure Cellular Data is toggled on. Also check the quick settings panel (Control Center) for the cellular data icon

Airplane Mode

Airplane Mode disables all wireless radios including cellular data. Check that it is off. Also try toggling Airplane Mode on for 10 seconds then back off — this forces the phone to reconnect to the cellular network from scratch and often fixes data connection issues.

Data limit reached

If you have exceeded your plan's data allowance, your carrier may have cut off or severely throttled your data:

Check your data usage: Android: Settings, Network, Data Usage. iPhone: Settings, Cellular, scroll down to see per-app and total data usage
Log into your carrier's app or website to check your current data usage against your plan limit
If your data is throttled rather than cut off, pages may technically load but extremely slowly (often 128 Kbps or slower, which makes most modern web pages unusable)

APN settings

The Access Point Name (APN) is the configuration that tells your phone how to connect to your carrier's data network. Incorrect APN settings are one of the most common causes of mobile data not working, especially after:

Switching carriers or inserting a new SIM card
Resetting the phone to factory defaults
Installing a custom ROM or major software update
Buying an unlocked phone that was not originally sold by your carrier

Check your APN (Android)

Settings, Network and Internet (or Connections), Mobile Network, Access Point Names
You should see one or more APN entries. There should be a selected (active) APN indicated by a filled circle or checkmark
If the APN list is empty or the settings look wrong, you need to add or reset them

Reset to default APN

In the APN settings screen, tap the three-dot menu (or Reset button)
Select Reset to Default. This restores the carrier-provided APN settings that should have been automatically configured when the SIM was inserted
Restart the phone after resetting

Manually enter APN settings

If resetting to defaults does not work or no defaults are available, you need to enter APN settings manually. Search for your carrier name followed by APN settings (for example, T-Mobile APN settings or Mint Mobile APN settings). Your carrier's support website will have the exact values.

The key fields to fill in:

Name: Any descriptive name (like your carrier name)
APN: The access point name (this is the critical field — must match your carrier's specification exactly)
MMSC: The MMS center URL (needed for picture messages)
MMS Proxy: MMS proxy server (if required by your carrier)
MMS Port: MMS port number (if required)
MCC: Mobile Country Code (usually auto-filled from SIM, 310 for US carriers)
MNC: Mobile Network Code (auto-filled from SIM)
APN Type: Usually default,mms,supl — some carriers require additional types
APN Protocol: IPv4/IPv6 or IPv4 for most carriers

iPhone APN

iPhones manage APN settings automatically through carrier settings updates. You cannot manually edit APN settings on most iPhones unless using a carrier that requires it:

Go to Settings, General, About. If a carrier settings update is available, a pop-up will prompt you to install it. This update includes the correct APN configuration
For carriers that do support manual APN: Settings, Cellular, Cellular Data Network. Enter the APN values provided by your carrier

SIM card issues

Reseat the SIM: Remove the SIM card (use the SIM ejector tool or a straightened paperclip in the SIM tray hole), wait 30 seconds, and reinsert it firmly. A SIM that is slightly loose or not making full contact can cause intermittent data failures
Clean the SIM: The gold contacts on the SIM card can get dirty or oxidized. Gently wipe them with a clean, dry cloth
Test the SIM in another phone: If you have another phone available, put your SIM in it and test data. If data works in the other phone, the problem is your phone's settings or hardware. If data does not work in the other phone either, the SIM or your carrier account is the problem
SIM card damage: Physical damage to the SIM (cracks, chips, bent contacts) causes data failures. Your carrier can replace a damaged SIM at their store, usually for free or a small fee

Network settings reset

If nothing else works, resetting all network settings restores everything to factory defaults:

Android: Settings, System, Reset Options, Reset Wi-Fi, Mobile and Bluetooth. This clears all saved Wi-Fi networks, Bluetooth pairings, and cellular settings including APN. The phone will re-download carrier settings when it reconnects
iPhone: Settings, General, Transfer or Reset iPhone, Reset, Reset Network Settings. Same effect — clears all network configurations to defaults

After resetting, restart the phone. The carrier should automatically push the correct APN and network settings. If it does not, manually enter the APN settings as described above.

Carrier and account issues

Provisioning: Your phone line may not be properly provisioned for data on the carrier's side. This commonly happens with new activations, number ports, and plan changes. Call your carrier's support line (from another phone if yours has no data) and ask them to verify that data services are provisioned and active on your line
IMEI block: If the phone was reported stolen or has an unpaid balance from a previous owner, the carrier may block its IMEI from accessing data. Check your IMEI status at your carrier's website or by contacting support
Plan does not include data: Some very basic plans or voice-only plans do not include mobile data. Verify your plan includes data service

Network mode

If data works intermittently or only in certain locations, the network mode setting may be preventing the phone from connecting to the best available network:

Android: Settings, Network, Mobile Network, Preferred Network Type. Set to 5G/LTE/3G/2G (Auto) or the highest available option. If the phone is set to a specific mode (like 3G only), it cannot connect to LTE or 5G networks even when available
iPhone: Settings, Cellular, Cellular Data Options, Voice and Data. Select 5G Auto or LTE for the best automatic network selection

Software troubleshooting

Restart the phone: A restart reinitializes the cellular radio and network stack. This clears temporary states that can block data
Software update: Check for system updates. Carrier connectivity improvements are included in both operating system updates and carrier settings updates
VPN interference: An active VPN can interfere with mobile data in some configurations. Disconnect the VPN and test data. If data works without the VPN, the VPN configuration needs adjustment
Data Saver mode: Data saving features restrict background data for apps. While this should not block all data, it can cause some apps to appear as if data is not working when background data is restricted. Turn off Data Saver: Android: Settings, Network, Data Saver. iPhone: Settings, Cellular, Cellular Data Options, Low Data Mode

Mobile data repair in Marion

If your phone's mobile data is not working and the troubleshooting above did not fix it, Marion Phone Repair can check your SIM card, APN configuration, carrier provisioning, and phone hardware to diagnose and fix the data connection issue.