I have the same problem. Both my MacBook Pro (16 inch 2020) and Mac Mini (2020) shows "Device Timed Out" whenever I try to sidecar into my iPad Pro (2019).
haruishi
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution
From
Tokyo, Japan