Good Day

I bought a TP link RE 200 Wifi Extender Extender from a neighbour and I need some help please.

I am trying to reset it, then set it up...I've managed to reset it but I'm struggling to set it up so that it links up with my current Router.

I have managed to get it to show up on the Available Wifi Networks.

Once it shows on the Available Wifi networks I am unable to log in because there is no wifi connection therefore I cannot get onto the page to set up new password as well as linking it to the router.

May you please offer me some advice to sort this out. 

Thank you.