Connecting To Server (Error code -50)

Hi guys, please tell me why this error appears when I try to connect mac operating system with server. If I try to access for sharing If I try to access to a specific share on it seems to work but going to the server then box appear and say with me for authorization and when I insert credentials the it fails also don’t appear any list of shared folders. I also describe all detail in original words so that you can understand nature of the problem easily.
Error:
Connecting To Server
Sorry, the operation could not be completed because an unexpected error occurred.
(Error code -50)
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