Hi anton kalachev,
Welcome to the Tableau forums
First thing: "predefined random folder". What do you mean by Predefined Random? Is it random or predefined?
Second: Do you use the full UNC path to connect to the file? Server will need your connection to say: Connect to "\\fileserver\myshare\myfile.txt" rather than a mapped network drive such as "H:\myshare\myfile.txt".
The other problem might be that "Include external files" was checked in the Publish dialog in Desktop. It shouldn't be. Leave it blank if you want Server to refresh the extract from the shared file on a schedule.
Let me know if you need further assistance
Lénaïc RIÉDINGER, Global Community Engineer Tableau
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I assume you are referring to files like adding a robot.txt file, or adding an html page at a static path that can be accessed by other software validating that file is present on Tableau Server? As noted in the community page you linked, this functionality is not part of Tableau Server. The webserver that is used to provide Tableau content is not intended to have external files added to it.
If you have a proxy in front of Tableau Server, you could use it to host these files.