Cannot verify file exists with File.Exists when check file in SharePoint using SSL

Hi Experts

I am writing a code block where I need to check if a file exists in SharePoint. I am using the File.Exists method to check if the following file exists in SharePoint:

\\DavWWWRoot\sites\My-Site\Shared documents\General\MyFile.xlsx

However the File.Exists returns true on one machine but false when running from another machine. If I open the file using Windows Explorer the file opens fine on both machines.

I found that on the machine where I cannot use File.Exists on the filepath mentioned above it will return true if I remove the @SSL part from the file path.

Clearly it is some setting on this machine that is missing but I am not quite sure where to look.

NB! For both machines I have opened the SharePoint site in Internet Explorer in order to authenticate first.

Any ideas?

What happens if you remove @SSL when using the URL on both machines?