[4.6.1]Can't connect to dedicated server

[link text]1Hi, there:
I’m practicing to setup a dedicated server from the example project “ShooterGame”.
I reference the two official documents:
Dedicated Server Guide
Standalone Dedicated Server
I built binary ShooterGame server and client executable files and run them successfully, but on the client side, no matter I type “open 127.0.0.1:7777” or click “JOIN” on the game main menu to find the server in the server list.
I neither connect to the server and find the server in the list.
But if I run two clients, set one to be host, then the host will appear in the server list.
Any advice?

Best Rgards.