21

Quick Fix

Restart your iPhone, then check Wi‑Fi settings. If the error persists, reset network settings: Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings.

What it Means

Error 21 indicates a network connectivity problem where the iPhone can’t establish a stable Wi‑Fi or cellular connection. It often appears during app launches or system updates.

Possible Causes

• 1
  Weak Wi‑Fi signal or router issues
• 2
  Misconfigured network settings
• 3
  Software bugs in iOS
• 4
  Outdated firmware on the router or iPhone

Step-by-Step Solutions

1. Restart Devices

   Turn off your iPhone and router, wait 30 seconds, then power them back on to clear temporary glitches.

2. Reset Network Settings

   Go to Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings. This removes saved Wi‑Fi networks and passwords, forcing a fresh connection.

3. Update iOS

   Navigate to Settings > General > Software Update and install any available updates to fix known bugs.

4. Re‑enter Wi‑Fi Credentials

   Forget the Wi‑Fi network on your iPhone, then reconnect by entering the password again to ensure correct settings.

5. Check Router Firmware

   Log into your router’s admin panel and apply any pending firmware updates to improve compatibility with iOS devices.