When your Mac computer is using Web and Cloud Access or Web Security Service, Apple TV no longer works.
Web and Cloud Access or WSS
Apple TV will not work whilst a full tunnel VPN is active, filters cannot be matched to exclude it.
AppleTV will not work and cannot be filtered from full tunnel VPN. Either use WSS/Web & Cloud Access or AppleTV, not at the same time. At this time, several Apple features do not work well with security products due to the limited configuration of their network usage (ports and protocols). This may be revised in the future if there are any changes to the behavior of certain Apple features.