I found similar problem, but in my case, it sometimes works and sometimes not. Sometimes, the AVAudioSourceNode respect requested format (1 channel, int16, 48000) and sometimes I have same result as you - 44100Hz, 2 channels, floats. I wanted to rewrite my c-api based AudioUnit code, but it seems, that AVAudioEngine is too blackbox, very difficult to debug problems like this. Have you found any solution?

Hi, thanks for the answer. The problem is, that we are not able to simulate this. This crash never happens on our devices, but to relative big amount of customers in release build. Also the problem with Zombies enables it, that we got out of memory very quickly. We have video transmission app and that encoded frames, that are not removed from memory with zombies enabled made out of memory in seconds... Jindrich

I had similar problem - it looks like that IP address was blocked by Apple for some reason. It was IP address that was assigned to our server by Digital Ocean k8s node and probably reused from project that was not used for legal activity. When I recycled the node (and new IP address was assigned) the problem disappeared.