Hi @Joseph_K,

Could you describe your problem in more detail.  Are you having a problem streaming on the Apple TV (e.g. buffering / stuttering) or is the Apple TV causing issues with your Wifi?  If you stream from your phone over the same Wifi, how does that work?  Which model Apple TV is it?  4k?

I'm assuming the former (poor streaming).  And I am assuming by "dual bandwidth" you mean Band Steering?  Definitely turn off Band Steering, and make separate SSID's for your 5.8GHz and 2.4GHz radios.  Join the Apple TV (and other high-performance products, iPhones, iPads, laptops, etc.) to the 5.8GHz SSID ONLY.

Set the 5.8GHz SSID to us 80MHz BW (not 20/40/80).  And choose the least used channel (us inSSIDER or similar) manually.  Set the transmit power on the SSID to Custom and use a power between 16 and 20 dBm,

Set the 2.4GHz SSID to 20MHz BW (not 40 or 20/40).  And choose the least used channel (us inSSIDER or similar) manually.  Set the transmit power on the SSID to Custom and use a power between 12 and 16 dBm.

Ideally use Ethernet for streaming devices when possible.  Or MOCA, etc.

Also be sure all of your firmware's are up to date.  EAP245 firmware, Omada/OC-200, Apple TV, etc.

Do you have other streaming devices in your home?  Roku, Google TV, etc.  How are these working?

-Jonathan