OS VIEW CLIENT disconeted after a successful login

HI, my environment is as follows:

I. VIEW client has been set up connection to the server, and aslo  set up a secure server

II for port mapping, and the domain name resolution, the situation is as follows:

1. The network PC through normal sign VIEW CLIENT normal

2. external network PC through normal sign VIEW CLIENT normal

3  OS VIEW CLIENT disconeted after a successful login.

So how can i fix this issue.

Thanks!