What's the model number of your extender? It may be that your computer connects to your router not the tplink network. By the way, the extender has the same password as your router. Is it because you've changed the password on your router, so you want to change it on the extender. I suggest you just reset the extender then connect your phone or computer to the tpink extender network, which will not have internet access, but you can login tplinkrepeater.net then. Many people would connect to the router network because they think the tplink network is not working. It's how to login the extender.