SMBv3.1.1 disconnects and fails to reconnect on Windows 10

Be warned: This will be a long one with a lot of text and few images. I never planned on doing a write-up on this issue, so I did not take a lot of pictures.

I have been troubleshooting this issue on and off for two years, and I was on the brink of giving up several times. I pride myself in finding solutions where others only find stress and hair-loss, and do so routinely, but sadly there are still nuts I cannot crack. This issue was believed to be such a nut. But I was wrong. The solution had been staring me straight in the eyes for quite some time, but we must not get ahead of ourselves. Let us start at the beginning.

Problem

SMB sessions are invalidated, such that it is impossible to reconnect. This happens only on Windows 10 clients, Windows 7 and 8? clients running SMBv2.* can still reconnect as normal.

User story:

  • The user opens a file explorer window and navigates to a folder on a fileserver containing documents the user wants to read and/or edit.
  • This works without issue 100% of the time as long as the client computer has a network connection to the file server.
  • After a period of inactivity the SMB session is suspended. The user does not detect this, everything is still ok.
  • Some time later, the user will either
    • Try to save a file
    • Try to open a new file using the same File Explorer window
  • Possible outcomes
    • Everything works as expected
    • It is impossible to save the file to the server, it has to be saved locally.
    • The File Explorer window is gone. The user has to re-open the window and navigate back to the folder in question.
  • Thus, the user gets annoyed and and complains about the stupid Windows 10 upgrade, which is understandable.

Relevant Event IDs: 30807 from SMBClient and 1016 from SMBServer.

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