http://www.mywifiext.net is local webpage provided by NETGEAR to its user, so that whenever they want to either configure their range extender or want to change already assigned configuration, they can do so with utmost ease. Thus http://www.mywifiext.net works as interface between user and NETGEAR wireless range extender device.
Although whenever user want to search about www.mywifiext.net setup page it can done by entering both http://mywifiext.net, https://www.mywifiext.net, http://www.mywifiext.net, http www wifiext net. Both of them will deliver you same result. Thus all of them are just different way of searching about http://www.mywifiext.net in your search engine.