How can I get the connection numbers in a connection in local network with NetworkDiscovery?

Hi, I am doing something like matchMaker in local network.

Here is my problem:
First, I used NetworkDiscovery to start a server,
Then, in the client side, I used NetworkDiscovery to discover the server and then connected to it

Question is, how can I know how many clients connected to the current server?

I used to save the number in NetworkDiscovery.broadcastData, but finally found the value cannot be changed after the server is started, that is zero always!

So, how can I get through it...

How can I get the connection numbers in a connection in local network with NetworkDiscovery?