HI @P_flwrs, welcome to our forum. The “Mi box S” runs Android, and the iTV app is available on Android: KPN Interactieve TV | Play Store. I don't know how it will run on this device, since it was designed for mobile devices but if the Mi Box S has the required specs it could work.

The homeplug has no effect on the router and vice versa. The router only sees a UTP-cable, wether it's connected to a homeplug, switch, pc or tv-receiver doesn't really matter for the router.