C++ hangs when working in thin client

Jan 22 at 10:19 AM
We have c++ installed on the server,and there are 15 clients accessing server at the same time.Some systems function well without hanging while some systems just hang.
The server is on windows server 2012.Is it the problem of c++ on network or network issue?we tried increasing the ram size,but did not got desired results.Please help as my students have to finish their portions.