So... Quite an adventure.

I am with Xfinity, and have a Arris Surfboard as a modem/router. 

On the Arris modem/router, I've disabled by previously active 5Ghz and 2.5Ghz Wi-fi networks to avoid interference.

Set-up Deco. So much trouble...

Only a few devices can connect. iPhones cannot. 

The overall message I get on the iPhone is that there are network interferences. I'd like to set the Mac channel for my Deco wi-fi, but there is no option to do that on the Deco app.

Anyone has any suggestion before I return all of this? So far, it's been 2 weeks of frustration. 

Thanks!