I have already tried all of these things. Also a full factory reset, no change.
As explained moving the roku device isn’t plausible, neither is moving the Router. The router is a brand-new Linksys mesh Velop Router, it isn’t sensible to suggest buying a new router as it’s only two months old and pretty high spec too.
I’m unclear why all other devices in the room behave fine, but the Roku does not. Do newer Roku models have improved antennae? I would consider buying a new Roku. Do any Roku boxes come with ethernet anymore?