Xbox beta iOS iPhone

I believe so yes. All IOS devices.

I wouldn't say "All iOS devices", cause that would mean a first Gen iPhone/iPad could use the service. If at all possible I'd say everything that uses iOS 12 and up, because iOS 13 is currently in beta (with a Sep. release).

I've been using iOS 16 on the Beta for a while and it was fine, its only the last few days its stopped working for me (iPhone 11 Pro)

Hello ARLETHEPOSS, this is Manuela. I'm an Independent Advisor and community user like you, ready to assist with this.
Not a Microsoft employee.

This could be caused by the iOS beta and not an issue with the cloud gaming feature itself.

May I know if you can go back to a stable version of IOS, or if you have close another iPhone with iOS 16.5 or less, verify the cloud gaming feature there?

iPhone 4 is End Of Line and doesn't use the latest version of iOS so they could be the problem. I can confirm it works fine on iPhone 8 and iOS 12

Hello, AlricLM. I'm Arturo, and I'll be glad to provide assistance with your inquiry today.

I'm sorry to hear you're having trouble with the sound when using the remote play feature on your iPhone.

Not only that, AlricLM, but I would like to ask if you tried some troubleshooting steps on your iPhone to discard everything else?

In case you didn't perform troubleshooting steps, I would like to suggest some before considering reporting the problem to Microsoft:

A. Reinstall the Xbox app on your iPhone.

B. Make sure that your iPhone is running the latest iOS update. You can check for iOS updates by opening Settings > General > Software update.

Note: If maybe your iPhone is running a beta version of iOS, it is recommended to go back to a stable version before trying the remote play feature.

C. Try to temporarily connect your iPhone to a different Wi-Fi network before testing the remote play feature and the sound quality.

Regards,

Arturo.