?nginx-push-stream-module doesn't return more than 15,000 subscribers. Where to dig?

Question

Nginx

Installed nginx-push-stream-module on the server . Does not give more than 15,000 connections.
I have each channel - 1 max_subscribers connection specially costs 1, as a result, a maximum of 20,000 channels are opened, with a maximum number of 15,000 subscribers (I look at the statistics of the module).
Memory set to 16GB.
Users somewhere in 2 times more really.
In the morning, when online is small, it grows at the same time as subscribers, after reaching 15,000 it does not grow at all.
Silence on all logs. Most likely a plug on the server, but where to look for it??

Answer 1

look at server logs, look at dmes, look at server monitoring.

Answer 2

Got it?