I have three FireTV devices and none of them are able to play Prime Video anymore. Error code 5505 which typically indicated that you are out of content right zone.
Have done all possible troubleshooting including changing address in the settings and made sure that all units are upgraded.
Netflix and others works fine confirming connectivity.
Watching Prime Video on my laptop from the same network also works which clearly indicated a problem with FireTV and Prime Video.
Appreciate any help to resolve this one since the chat helpline was not able to provide guidance.
Turn off any VPN you are using. Report back.