The thread I referenced earlier (Switching daily between Roon core on work vs home computer?) explains how to switch cores.
The purpose (for me) was to use Roon both at work and at home. Another scenario in which I might switch cores is if I experience internet issues when at home. In that case I can move my local music (which is on an external portable disk) from my Roon-dedicated computer downstairs to the computer upstairs that I’m working on, and switch to the core on the upstairs computer. Then I can still play at least my local music.
HTH…