Firmware upgrade to 9177 on AC87U causes NAS to never sleep

I have the RT-AC87U Asus router. I was running version 5134,but recently upgraded to 9177. I now notice that my Synology NAS never goes to sleep. My previous router( Dlink) caused this too- that's one reason i bought the Asus. I understand this non-sleeping is caused by some packets the router keeps sending, polling the network asking who's out there on my network. ( note I am a network novice- apparent huh).

Is there a setting I can alter to will allow my NAS to return to it's sleeping...

Firmware upgrade to 9177 on AC87U causes NAS to never sleep