Device shown active on RT-AC86U after it is turned off

[Boomeral]

I noticed this anomaly the other night.
Took away the cell phone from my kid and turned it off. Logged in to Asus router and checked "Adaptive QoS" section. The device was not only listed in this section but showing data transfer activities. Curious, I then placed the device in an airtight metal canaster. Yet the activities, even half an hour later, continued. Attached screen capture was taken half hour later.
It only shows the activity at the time of the capture; however, other services were appearing and disappearing consistently.

Does anyone have any idea what might have caused this odd behavior?

The RT-AC86U is running firmware 386.14_2.

Have not noticed any other unusual behavior from this WiFi router.

Thanks in advance for any resolution.

 

[degrub]

Usually, Faraday cages must be earthed to properly shield in my experience. And the device inside isolated from the metal cage.

And yes, even if a phone is turned off, it may not be fully "off" . We used to pull the batteries when that was feasible.