file.Exists() returns false although I can reach these remote files from file explorer?

Because I have authorization, I can reach files that in another server via file explorer like this:

When I want to download items from that folder in a web project, I get "false" from file.Exists() method. My code is below. What is wrong?

fileNameToShow = fileNameToShow.Replace(" ", "_");
var fileNameAndPath = "\\\\supplier\\SupplierFiles\\Live\\20\\290B_T.N.E.JPG";
FileInfo file = new FileInfo(fileNameAndPath);
file.Refresh();
if (file.Exists)
{
 // Send the file to the browser
     Response.Clear();
     Response.AddHeader("Content-Disposition",
                    "attachment; filename= " + fileNameToShow + "; size=" + file.Length.ToString());
     Response.TransmitFile(fileNameAndPath);
     Response.Flush();
     Response.End();
 }
 else
 {
     throw new Exception("File does not exist!");
 }