Smartfoxserver reconnect problem

I have developed online texas holde’m poker game with Unity 3D and SmartFoxServer for multiplayer.

I would like to know how to user reconnect previous session when the user close the app and than re-open immediately. (In plenty of mobile games users can do that.)

In SmartFoxServer, I set the ‘user reconnection time’ is 30s, besides force logout is off.

I searched all forums and docs for Smartfoxserver but I couldn’t find anything but Smartfoxserver HRC system, and couldn’t use also HRC system while I couldn’t discover any sufficient documentation or information about it.

Can anyone assist on me? What should I do?