Some iRoot versions for Android 4.4.2 can work offline, but most will attempt to download exploit packages. Ensure your Wi-Fi is stable and that no firewall is blocking the app.
If the APK version fails, try the iRoot for PC version. Connecting your phone via USB and using the desktop software is often more powerful for stubborn 4.4.2 devices. Download Iroot Apk For Android 4.4.2