Hi Michiel,

Thank you for uploading these files. I did check on them and agree with
you, this issue is weird.

"DFSUTIL /PKTFLUSH" seems work partly. I suspect the issue could cause by
following factors. Could you please help me check them?

1. A security/network software (such as antivirus or accelerator)holds this
setting.
2. A third party software holds this setting.

Could you please take a clean boot to test this issue? I suggest you
temporarily remove antivirus to test the issue if possible.

Clean Boot
========
1. Click Start, type "MSCONFIG" (without the quotations) in the Search Bar
and Press "Enter" to start the System Configuration Utility.
2. Click the "Services" tab, check the "Hide All Microsoft Services" box
and click "Disable All" (if it is not gray).
3. Click the "Startup" tab, click "Disable All" and click "OK".
4. Restart the computer and test the issue.

Also, please close all open windows before putting into standby.

If the issue still persists, please feel free to let me know. I will
involve my colleague work on the problem.

Thanks.