Iphone 5se 2016 would not remote ATV4. 3-4 calls at Apple support and updates to iOS and TVOS to get the same version seem to be not required after all.
Above post helped!
The following assumes that remote has already been added to control center.
So I :
Signed out of iCloud on ATV4 by doing the following to / within the ATV4:
( Settings>Users and Accounts>then picked the problem User>iCloud>Sign Out.
Then on Malfunctioning iphone, the ATV4 was removed from the list at the bottom of the Apple ID page by the following steps: >Settings, at the top of the page choose the cell with your your AppleID showing, then scroll down the page that comes up until you see the ATV4 listed and choose “Remove from Account”.
- Now, still on the iPhone, swipe up to get the control center screen, tap the remote icon and wait for the 6 digit security code to show on the iPhone and enter it onto the TV screen using the ATV4 dedicated remote. Wait a few seconds.
- BINGO - the iPhone’s remote control for ATV4 now works !
- It seems to be “the old log out then log back in trick” to fix it.