Have you tried downgrading the Plex server version to 2.4 and see if it resolves the issue?
If it does, then it’s related to an already reported problem, thread here:
General consensus is to temporarily downgrade the server to 1.24.5.5173 as a workaround, while we wait for a fix from the Plex devs.
Another way to help test would be to force transcoding on 1.25.7.5604, by disabling DirectPlay and DirectStream. This will force the server to transcode the audio, and if it still cuts out, it may be unrelated.
If it doesn’t solve the problem, can you please post:
- the steps you went through to troubleshoot the problem
- the server(s) and client(s) versions you are using
- prepare your error report like this
The problem needs to be reproducible, so server and client OS info; setup method; example file etc. All are helpful in figuring out the problem.
Anyway, good luck, I hope you find help 
