To answer the question of ‘what is mywifiext’, it is important that you try to install the extender without using the web-based interface. You can try hundred times, but you will not able to setup the extender. So, you need mywifiext to complete the setup process. Mywifiext is the local web address that lets you configure the extender so that you can use it without any issue. If you are not able to access this local web address, then you should take help of tech experts.