I recall with the release of Roon 2.0, one of the stated capabilities was that Roon Remotes at differing versions would be able to access the Roon Core

Roon Software Discussion
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@simon_pepper don’t forget that in-place downgrade from Roon 2.0 to 1.8-Legacy is no longer supported since Nov’22 - Roon 2.0.3 and ARC 1.0.4 are live!