Can't access devices connected to extender from main network

I have the R8500 and a D-Link DAP-1520 extender.  All works fine except I connect to the router by wifi and can't see the computer that is connected to the extender.

Is this normal?  If not, it maybe that this is a cheap extender without much for settings.

Looking for help solving this.  If I need a new extender, what is recommended to go with this router (if that matters), or is a mesh network a better way to go?

A mesh system would be more expensive,so hopefully I can either make this one work in that regard, or buy another model that isn't too expensive.

Thanks for any input.