referring to the bad internet connection issue trying to play Apple TV plus on firestick I found a solution that works for me, just reboot the fire stick. Go to settings, fire stick and then reboot, then open Apple TV plus and will work. I try before reinstalling the app and didn’t work but rebooting firestick makes Apple TV plus to play
Another thing that worked for me - I'm not entirely sure which specific one - but I turned on some of the fire stick privacy settings I had turned off (eg, usage, personalised advertising, featured content, allow auto play, etc) and the setting that I think was under settings > application management > apple TV... And switch back on the one about allowing all links to open.
After two days of fiddling with DNS, reinstall, etc etc etc that finally worked.
Apple TV plus don’t play in Amazon firestick
