APN Not Working? Fix Mobile Internet & MMS

This is the single most common APN mistake. On Android, entering APN values and tapping Save does not automatically activate the APN — you must also select it from the list by tapping the radio button (filled circle) next to your new entry.

1. Go to Settings → Mobile Networks → Access Point Names
2. Find the APN entry you created
3. Tap the radio button (○) next to it so it becomes selected (●)
4. Restart your phone or toggle Aeroplane Mode

If you see multiple APN entries (some may have been pre-loaded), make sure the one you created — with your carrier's correct values — is the one that's selected.

APN values are case-sensitive and must be entered exactly. A single misplaced character — including a trailing space accidentally typed after the value — will cause the connection to fail. Common mistakes include:

1. Extra space before or after the APN (e.g. " everywhere" instead of "everywhere")
2. Capital letters where none should be (e.g. "Everywhere" instead of "everywhere")
3. Incorrect domain (e.g. "giffgaff.co.uk" instead of "giffgaff.com")
4. Using .co.uk instead of .uk (e.g. "goto.virginmobile.co.uk" instead of "goto.virginmobile.uk")

Solution: delete the APN entry entirely and re-enter it from scratch using the copy buttons on your carrier's page on this site.

Three UK carriers require PAP authentication — O2, giffgaff, and Lycamobile. If you're on one of these networks and haven't entered the username and password, mobile data will not work even if all other values are correct.

1. Go to your APN settings and tap the entry to edit it
2. Find the "Authentication type" field and set it to PAP
3. Enter the username and password for your carrier:
   • O2: username = o2web, password = password
   • giffgaff: username = giffgaff, password = password
   • Lycamobile: username = lmo, password = plus
4. Save and restart

The MNC (Mobile Network Code) must match your carrier's network. If it's wrong, your phone may either fail to connect entirely or connect with incorrect routing. UK MNC values are: EE = 30, O2 = 10, Vodafone = 15, Three = 20. MVNOs use their host network's MNC — for example, giffgaff uses MNC 10 (O2's code).

1. Open your APN entry for editing
2. Scroll to the MNC field
3. Check the correct value on your carrier's page and update if needed
4. Save and restart

This isn't an APN problem at all — but it's frequently mistaken for one. If your APN settings are correct but data still doesn't work, check whether your plan has remaining data.

1. Call your carrier's balance line or check their app
2. Most UK carriers offer a short code to check balance (e.g. *#100# on some networks)
3. On pay-as-you-go plans, confirm you have an active data add-on
4. On monthly plans, you may have hit your fair-use cap

If your allowance is exhausted, your carrier will typically show a data-used notification or redirect your browser to their top-up page.

If the APN edit screen is locked and you can't tap the fields, your SIM is pushing automatic configuration (OTA) that overrides manual settings. This is a carrier-level lock, not a phone fault.

1. Remove your SIM card, wait 30 seconds, reinsert it — this sometimes resets the lock
2. On Samsung: Settings → General Management → Reset → Reset Network Settings (note: this clears Wi-Fi passwords too)
3. On stock Android: Settings → System → Reset options → Reset Wi-Fi, mobile & Bluetooth
4. Check your messages for a carrier configuration SMS — accepting it may unlock the editor
5. If nothing works, contact your carrier and ask them to disable OTA APN configuration

If mobile data works but you can't send or receive picture messages or group messages, the MMS-specific fields are incorrect or missing.

1. Open your APN entry and check the MMSC, MMS Proxy, and MMS Port fields against your carrier's page
2. Ensure mobile data is active — MMS cannot use Wi-Fi. Temporarily disable Wi-Fi when testing
3. Check the MMS Proxy is an IP address (not a hostname) on carriers that require it
4. On iPhone: ensure the MMS fields under Settings → Mobile Data → Mobile Data Network are filled in separately from the data APN fields
5. Confirm your plan includes MMS — some data-only SIMs don't support picture messaging

If your APN settings revert to defaults every time you restart, the SIM is continuously overriding manual configuration. This is frustrating but fixable.

1. Contact your carrier and ask them to disable OTA (over-the-air) configuration pushes for your account
2. Try a different SIM — some older SIMs from when your carrier had different settings will always try to push outdated configuration
3. On some Android phones, you can set the APN type to "default,supl,mms,dun" — the extra "dun" type prevents the SIM from overriding
4. Request a free SIM replacement from your carrier — newer SIM cards often don't have this issue