I love 4k, and I love these Xi6 boxes (that can be wireless, if needed)

and unlike the dvr box, these Xi6 boxes can do Dolby Vision.

How many of these Xi6 boxes can I have (along with the 4K DVR box?) - this past fall, for football season, I utilized the 1 4K DVR box and 5 Xi6 boxes, am wonder if next season I can add another Xi6 box

Would it better if I connected them with an ethernet cable than to use them wirelessly?