I connect everything direct to the Apple TV. If you can avoid using the Companion app for pairing, do so. Not that the Companion app does not work, but that is an additional layer which means another possible source of problems.
First ride was great! The graphics are amazing on the Apple TV versus my old computer. However my cadence is always in the sixties and I am spinning much faster than that. I have a tax flux doing the sensing.
Is there some firmware or something I need to update?
Use ATV connections and if you use the LAN connection instead of WIFI it will be rock solid.
Always check you are on the latest firmware - many smart trainers have only recently included cadence as part of the connection.