make sure the green light on the extender is turnd on after you plugged into the wall
Try http://192.168.1.250 if http://www.mywifiext.net does not work
If you still cannot access the extender, plug in a lan cable into the lan port on it bottom and connect it directly to your router. Then you should be able to access it via http://192.168.1.250
Configure your repeater:
4.1 Chose the Wifi you want to extend
4.2 Enter the password and keep the same security policies
4.3 Do NOT use the suggested SSID because it ends with _EXT. Instead remove “_EXT”; this way your Wifi devices will not have to add another SSID.
It is perfectly normal that after you hit finish your browser displays page not found. The repeater uses DHCP and will get itself an new random IP.
Remove the lan cable and unplug the extender from the wall for a few seconds.
Plug it into the wall and everything should work fine.