How do I fix no service on a Samsung Galaxy S21 FE after an update?
Answer
After an OS update, reset mobile network settings and verify the correct APN; that clears most post-update no-service issues without erasing personal files.
Before you start: stop right away if…
- Resetting network settings deletes saved Wi‑Fi passwords on the phone.
- Signal booster apps from unknown sources can be harmful.
Follow these steps
Toggle Airplane Mode
Turn Airplane Mode on for 30 seconds, turn it off, and wait for signal bars to return.
You should see: Service returns temporarily or the outage continues.
Reset mobile network settings
Go to Settings > General management > Reset > Reset mobile network settings, confirm, then reconnect to Wi‑Fi as needed.
You should see: Cellular settings return to defaults and the phone re-registers.
Check and correct the APN
Open Settings > Connections > Mobile networks > Access Point Names and select or enter the correct APN for your carrier (such as Mint).
You should see: The proper APN is active and mobile data can connect.
Reseat the SIM and contact the carrier if needed
Power off, reseat the SIM, power on, and if there is still no service, ask the carrier to refresh the line or check compatibility after the update.
You should see: Service is restored or the carrier identifies a provisioning issue.
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Extra tips
What to look for: No service or dropping signal bars after an update, and Access Point Names under Mobile networks
Before you change anything: Note that a network settings reset removes saved Wi‑Fi passwords. Have your carrier APN details available. Confirm the SIM is active on the account. Never install random 'signal booster' apps.