Bearing in mind your location, I would guess an Australian native - Dendrobium, Dockrillia or related species or hybrid.
There are many species in this group and I don’t know them well. I do notice it looks like Dockrillia wasellii
Dockrillia wassellii | Orchids Forum
Or maybe a hybrid -
Den. Australian Purple Pepper
I’m not suggesting these are it exactly, there are many candidates - but a good place to start looking.
Usually, they are grown mounted. Most of the terete or semi-terete ones are lithophytes. Many of the terete species were hybridised with D. kingianum and D. speciousum, in fact there are thousands of hybrids (as I expect you know).
Cheers
Arron