Recently I have encountered the famous error 53 (network path not found) while connecting to network share folder using C# WinAPI. So typically first step is to really check whether path is existing with valid credentials and yes it was there and the credential is valid. After one hour of checking an rechecking I discovered that the path (folder) was a DFS (Domain based File Share).
Resolution: Get the actual folder path from the referral list in DFS tab of the shared path