With Hoppers & Joyes, you are dealing with MoCA frequencies on the line in the 650 MHz to 875 MHz range.
Cable TV and internet operates in frequencies under 1000 MHz, which is why there is a high probability for conflict.
Upstream frequencies are typically under 50 MHz, and the downstream path is anywhere from 50 to 1000 HMz. The problem is, the downstream path frequencies can be changed at any time by the cable company. So if they are using ~550, it may work for a while... Until it doesn't because they changed something.
You could try to use a
cable compatible MoCA bridge that moves the MoCA operating frequencies to over 1000 MHz so there is no potential for interference. I've never done that, and I don't know how that would work with Dish hardware such as a Joey at the location. No promises.
Here is another conversation on the same topic.
(Yeah, and don't expect an installer to take responsibility for this stuff. They may just swear up and down that it's impossible because it's way beyond their training to know or deploy these kinds of creative solutions. A local independent installer may do it, you'd have to ask first - see my signature.)