When you use Netgear wifi range extender there are more chances that you come across netgear_ext. It is the default network name your extender broadcasts which helps you to connect and extend your WiFi range. https://www.ganjingworld.com/news/1hr1olmr7kjA8jIQlj1PiCRfp1i11c/top-troubleshooting-tips-for-netgearext-issues