How many socket connections can the Play Framework (Netty) handle?

Question

I am developing a SPA application with a playback platform at the end of Back (v2.5).

As you know, Play (or Netty) can handle many connections because of its asynchronous I / O.

For each client, I want to open a socket connection.

1. How many parallel socket connections can the Play platform work with?

2. How does a huge amount of open socket connections affect overall requests / seconds?