How to fix Cellular Data Not Working After iOS 26 Update : iPhone 16

If you recently updated your iPhone to iOS 26 and found that your cellular data is not working, you are not alone. Many iPhone users are reporting that after upgrading, they cannot use mobile data, make or receive calls, or even use 5G/LTE properly.

WiFi continues to work fine, but mobile networks become completely unusable. This problem is making iPhones almost useless for daily tasks like calling, navigation, or browsing without WiFi.

In this post, we will explain the issue, possible reasons, and some fixes you can try.

Common Symptoms After Updating to iOS 26

Users who upgraded to iOS 26 reported the following issues:

Cellular data not working even with full bars.
Unable to make or receive calls on SIM or eSIM.
5G/LTE not loading data, even though signal appears.
VPN conflicts (some apps like AdGuard VPN caused network blocks).
Messaging issues, where deleted texts reappear.
Navigation problems, maps not updating without WiFi.

Why Is This Happening?

The most common causes include:

Bug in iOS 26 modem firmware – affecting how the phone communicates with carrier networks.
SIM tray issue – especially in dual-SIM models, where switching SIM slots sometimes helps.
Carrier settings mismatch – after update, the iPhone may not sync carrier settings correctly.
VPN or security apps – blocking mobile data after the iOS update.

How to Fix iOS 26 Cellular Data Not Working on iPhone 14/15/16

1. Restart and Reinsert SIM

Power off your iPhone.
Remove the SIM card.
Insert it again (try using the bottom slot if your device has dual SIM).
Turn the phone back on.

2. Reset Network Settings

Go to Settings > General > Transfer or Reset iPhone > Reset.
Tap Reset Network Settings.
Your phone will restart and network settings will reset to default.

3. Update Carrier Settings

Go to Settings > General > About.
If a carrier update is available, you will see a pop-up to install it.

4. Disable VPNs or Security Apps

Some users fixed the problem by deleting AdGuard VPN or similar apps.

Go to Settings > General > VPN & Device Management.
Remove any VPN profiles.

5. Toggle SIM/eSIM Settings

Go to Settings > Cellular > SIMs.
Turn SIM/eSIM off and on again.
This may force a “cellular update” and restore data.

6. Try a Clean Install

If nothing works:

Backup your iPhone.
Use iTunes/Finder on your computer to reinstall iOS 26 cleanly.
Do not restore from backup immediately, test cellular first.

7. Downgrade to iOS 18.6 (Temporary Fix)

Some users rolled back to iOS 18.6 where mobile data worked normally. This is a temporary fix until Apple releases a stable patch for iOS 26.

Final Thoughts

The iOS 26 update has caused serious cellular data problems for many users, especially on iPhone 14 and iPhone 15 models. While WiFi still works, the inability to use mobile networks makes the phone unreliable.

If the above solutions don’t work, the best option is to:

Contact Apple Support directly.
Report the bug through the Feedback app (if on beta).
Keep an eye out for upcoming iOS 26.1 updates, which may fix the issue.

Until then, try toggling SIM settings, disabling VPNs, or reinstalling the update to get your cellular connection back.