[BUG] Error in server after 64 connections

We are trying to make a dedicated server using UNET so we did some quick tests under Unity 5.1.3.
A serious problem we have is that server will significantly get error and stop receiving new connections after 64 connections.
Here's how you can reproduce it:
1. Call StartServer() in NetworkManager in editor
2. Start another client, connect to the server with StartClient()(localhost)
3. After the connection is established, call StopClient() in the client
4. Call the StartClient() again in the...

[BUG] Error in server after 64 connections