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Did the problem occur with previous BIOS versions?
Have you tried rolling back to an earlier BIOS revision? You can perform this task with BIOS recovery method.
Here is the link for earlier BIOS:Intel® Download Center
Instructions for BIOS recovery available below:
Same effect here (0050). My NUC is connected to a NAS via LAN. When sent to "powersave" (I am not using hibernation), the NUC wakes up unintentionally when data is sent to the NAS from a different computer. Interestingly, this happens only during the first minutes after the NUC has been put into powersave mode.