Can't Reset/Connect

Running Windows 10 throughout via ATT Internet router. After initial Extender installation, never able to connect to 2.4GHz network that had the stronger signal. Always defaulted to 5 GHz. When the 2.4 GHz network was selected, received a message "Can't connect to this network". Decided to reboot. Both 2.4 GHz and 5 GHz networks remained as "available networks"...never dropped off. Now I can't connect to either one. All I can connect to is the router itself across the house, similar to before the Netgear Extender was purchased.

When I select either Extender WiFi selections, I receive a reply of "Can't connect to this network". Never had any opportunity to reenter WiFi password.