Hi. I have exactly the same problem. After about 20 seconds it turns off...or at least the sound stops. 
also, after not using it for a while it can be tricky to get it to turn on at all. I too have changed the core, no improvement and sent logs. I am sure it’s the amp, but it’s very strange. 

How close is your iphone/ipad to your wifi router? Don't forget the i-device is having to receive the stream from the internet then transmit it out directly to the speaker so it needs excellent wifi signal to reliably work. Congestion on your wifi can also affect it, whether on your network, or on a neighbours' that's using the same wifi channel as yours.

ebnrob wrote:

How close is your iphone/ipad to your wifi router? Don't forget the i-device is having to receive the stream from the internet then transmit it out directly to the speaker so it needs excellent wifi signal to reliably work. Congestion on your wifi can also affect it, whether on your network, or on a neighbours' that's using the same wifi channel as yours.

If it's a internet source, then I understand that the Airplay Device (in this case the Shape) will open a direct connection to the internet, thus the iDevice is just doing the controlling.

Guy wrote:

ebnrob wrote:

How close is your iphone/ipad to your wifi router? Don't forget the i-device is having to receive the stream from the internet then transmit it out directly to the speaker so it needs excellent wifi signal to reliably work. Congestion on your wifi can also affect it, whether on your network, or on a neighbours' that's using the same wifi channel as yours.

If it's a internet source, then I understand that the Airplay Device (in this case the Shape) will open a direct connection to the internet, thus the iDevice is just doing the controlling.

Chromecast definitely works that way, Airplay does this for video but my understanding for audio was that it went through the device. You could test it by turning aeroplane mode on after choosing a playlist. 

Guy wrote:

ebnrob wrote:

How close is your iphone/ipad to your wifi router? Don't forget the i-device is having to receive the stream from the internet then transmit it out directly to the speaker so it needs excellent wifi signal to reliably work. Congestion on your wifi can also affect it, whether on your network, or on a neighbours' that's using the same wifi channel as yours.

If it's a internet source, then I understand that the Airplay Device (in this case the Shape) will open a direct connection to the internet, thus the iDevice is just doing the controlling.

When you play from Spotify or Apple Music or another source, your controller is downloading the stream, not the playback device, such as the Shape. You are simply sending the stream to the Shape via your router. Obviously a wired network helps, but like the other poster says, you still have to send the content, with a small delay, from the controller to Shape via router.

Your internet speed could also affect this as you'd to be able to download, buffer and stream and it might be the buffer which can't keep up, which would explain the drop-outs (these are from the controller, not the Shape).

Another thing to try would be to fix the IP address of the Shape. I had similar issues when I first purchased my A9 (and, ironically, when I used to have a very slow internet connection). I fixed the AirPlay drop-outs by making my A9 use a fixed IP which never changes, which massively affected the routing to the A9. 

moxxey wrote:

Guy wrote:

ebnrob wrote:

How close is your iphone/ipad to your wifi router? Don't forget the i-device is having to receive the stream from the internet then transmit it out directly to the speaker so it needs excellent wifi signal to reliably work. Congestion on your wifi can also affect it, whether on your network, or on a neighbours' that's using the same wifi channel as yours.

If it's a internet source, then I understand that the Airplay Device (in this case the Shape) will open a direct connection to the internet, thus the iDevice is just doing the controlling.

When you play from Spotify or Apple Music or another source, your controller is downloading the stream, not the playback device, such as the Shape. You are simply sending the stream to the Shape via your router. Obviously a wired network helps, but like the other poster says, you still have to send the content, with a small delay, from the controller to Shape via router.

Interesting, that wasn't my understanding.  Also, it doesn't seem to be a particularly 'network traffic efficient' method. In effect, anything being streamed from the internet would have to go through the router twice: Once on its way from the internet source to the iDevice, and then a second time on its way from the iDevice to the Airplay playback device.  This sounds a little illogical to me!

Anyway, it got me thinking as to why I thought it worked differently.  Most of my AV knowledge is gained either by experimentation or from this forum, so I did a little googling to try and find an alternative source that may have influenced my understanding.

I found this from FlatPanels: 

trackbeo wrote:

A cogent explanation, but not entirely complete. 

Login to view imagelink replied on Wed, Feb 3 2021 11:03 PM

I wrote it just before bed. Plus on a forum we ought to be....succinct!

I guess you are referring to the following:

"Say you for example browse the internet on your iPad and TV screen via AirPlay Mirroring, and navigate to a website with a video stream. When you click play the video stream will automatically utilize AirPlay instead of AirPlay Mirroring and stream from the internet source directly to the Apple TV box. When you stop the stream AirPlay Mirroring is seamlessly enabled again."

Airplay is not a protocol that can be used over Internet, the above article is misleading IMO. In this case the internet source does not Airplay to the target Apple TV, but instead the iPad gets the video stream from internet (e.g via HTTP) and pushes it to the Apple TV via Airplay. Airplay Mirroring stops at this time, i.e video will be only shown on the TV via the Apple TV, not on the iPad. It is similar to the iPad receiving a music source (e.g. Deezer) from the internet and sending the "sound" via Airplay to the target Airplay speaker without the sound being produced by the iPad itself.

mbolo01 wrote:

I guess you are referring to the following:

"Say you for example browse the internet on your iPad and TV screen via AirPlay Mirroring, and navigate to a website with a video stream. When you click play the video stream will automatically utilize AirPlay instead of AirPlay Mirroring and stream from the internet source directly to the Apple TV box. When you stop the stream AirPlay Mirroring is seamlessly enabled again."

Nope, I was referring to this bit:

"When using internet sources for watching video (such as YouTube or Netflix), something else happens when using AirPlay. When streaming from an internet source and pressing the AirPlay button on your iOS device, your AirPlay-enabled Apple TV box will open a direct connection to the internet source. Your Apple TV is being authorized to access the internet source and no streaming occurs between the iOS device and Apple TV, thus no loss of quality. The video or music quality is as good as the streaming service allows."