A. 1. Ensure that your iPhone is connected to a stable Wi-Fi network. Go to Settings > Wi-Fi and check your connection.
2. Restart your router to refresh the network connection.
3. After reinstalling the app, try logging in again and ensure that you have entered the correct credentials.
B. 4. If the issue persists, try resetting your network settings by going to Settings > General > Reset > Reset Network Settings. Note that this will erase saved Wi-Fi passwords.