ATV 3 airplay disappears when on 5g

Hello. For some reason my ATV3 will disappear from my network after about 15 minutes when it is connected to my wireless router on 5ghz band. on 2.4 it stays and there are no issues, but i would love to use the 5g as it is apparently better for HD streaming. The ATV itself works fine even when my iphone or ipad2 cannot see it (ie. airplay disappears). It will stream netflix without issue, but I cannot airplay anything to it.

I can make it reappear if I unplug the ATV or reboot the router, but the issue will recur.. My router is an ASUS Rt-n56u.

I would really appreciate some help with this.

Thanks.