There must be a correct connection between your router and extender. To verify this, check the LEDs on your extender and confirm that each one the lights are showing green. If not, power cycle the extender by removing its power adapter from its electric source and insert it back after a while.
If you've got used a coaxial cable to attach your devices, check it for any cuts or breakage. If any crack is found within the wire, replace it with a replacement one.
mywifiext.local not working issue also can occur if your extender is found at a far distance from your home WiFi router. In such a situation, consider locating your Netgear range ext a touch closer to the router and confirm no WiFi-interference devices are hindering the signals.
Needless to say, but check whether you've got turned on the facility button of your extender. Also, if you've got plugged the device into an influence outlet that's not providing sufficient power supply, then also mywifiext.local won't work for you. So, change the facility outlet of your extender and see if it works for you or not.
Use of an outdated browser are often one more reason behind mywifiext.local not working. To urge this fixed, update your browser also as consider wiping off the clutter of cache, cookies, and history from it so on avoid any longer browser-related issues.
If you own a MAC or iOS device, then only mywifiext.local will work for you. On the Windows OS, you're advised to access your extender's login page via mywifiext net.
Confirm there are no typing mistakes within the web address. one typing error within the URL can take you to the third-party website or show you a mistake message saying ‘Unable to attach to the internet’. Though the meaning of the message will be an equivalent, notification wordings can vary as per the utilization of your browser.
Temporarily disable the firewall or ad-blocking application on your computer to see if the matter is said to such applications.

It is expected that after giving the above troubleshooting tips a try, you'll be ready to access the Netgear extender login page via mywifiext.local. Regardless of whether you're accessing the online address that extender model, the ideas will work an equivalent for all.