Hello,

There are a couple of things which could be causing the issue  but this error is somewaht generic. Check that your version of Windows is released in V14 Sp1 as this really matters in whether it will work or not. Next, the faq below is a many year collection of things which are known to make server and client connections work. LmHosts file configuration is very important , so us this a checklist to eliminate potential causes. Also, check if you can use the Simatic Shell and use the interconnect options at the client with the project on server.  This way can give clues to the issue like windows authentication. Mostly, I make all servers and clients with the same windows user name and passwords to make Windows more happy. 

https://support.industry.siemens.com/cs/us/en/view/868014

Thanks,
Steve