Peter take a look at this with another user who had problems with Andrtoid.
It might help you Android remote app doesn't work - #7 by Rugby
Certainly turn off battery optimisations etc. I have the same issue on my 1st gen iPad Pro, there is not enough memory for Roon so it keeps putting it out of memory and restarting it, and it is a pain. None of my Android devices suffer this as I have disabled it