Yup, you and everybody else with slow internet (including me) gets that same message when trying to download 4K from the internet.
Sad, but very true.

In any case, Dish must know that the majority of their clients live in places where internet (if any) is slow. Maybe it's just an H3 bug(?).
BTW - the Channel 1 pre-loaded VOD is a great idea! Just need better selection of 4k movies. Still early but they're coming!