RBR50 Extender

Hi,

I am from Germany and very new in the USA and I have a question. I use the Orbi RBR50 Router and an Extender (Satelite).

I want to expand my range and want to buy a new 2nd Extender (Satelite). But I can't find anywhere such an Extender.

What has happened? Is this model, I bought only a few month ago so old, that it will not be supported? And if this is the case, which expander I shall buy, that's fit to my system?

Thanks for a reply.