Doesn’t happen all the time , it’s when watching Apple TV 

That’s strange as the Ace is communicating with the sound bar and not AppleTV (ATV). Could it be that your ATV is losing connection to the Apple and/or downloaded streaming app server 

Depends, doesn’t it? The OP could be connecting to their AppleTV with a Bluetooth connection, rather than directly with the Sonos swap to the soundbar. 
 

Two questions for the OP…

1. what type of connection are you using for your Sonos Ace?
2. Have you called Sonos Support to discuss it?

   When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

Thanks for that , it’s now happening with Amazon , watching film , doing it again , so do you think I should contact Sonos surport then ? 

Yes.

​@Casper1972 What about answering the questions ​@Airgetlam asked you?