Disk Drive Activity

I am seeing activity on a disk drive I connected to my router via USB 3.0. I see what looks like both reading and writing. But I am no running anything on my computer to access the drive. I have even notice this activity when my computer is turned off. Is the router doing this on its own, or is there some other possible source? I have checked the contents of the drive and can find no evidence that anything was changed.

I have an R7000 Dual Band Gigabit Router, but my model is not listed in the list provided by the web site.