My extender is connected to my existing home network fine, and it's created a new network, but the password it's created is just totally random and due to character length (around 90 characters) totally un-usable as most of my devices only have a 60 character limit. 

My actual WiFi password is about 15 characters, and that is the exact password I used to connect the extender to it. 

However, when logging into the Tether app, it shows my main WiFi network correctly,but the password as some random unknown 90 characters, which it's then duplicated for the extended Network. 

I cannot figure this out at all, and there doesn't appear to be anything in my router settings either. 

I bought the extender as I had to move my router for work reasons, which left a dead spot for signal at the back of my house, but since then I've only managed to connect my outdoor camera to it, because that had 100 character limit, things like my TV and smart speakers etc have much smaller character limits and I can't therefore connect them as there seems to be no way to change this random made up password it's showing.