Joanna is having trouble with streaming video frequently stopping and downgrading in quality on her Roku. It's only about 6 feet away from her router, and she even hard wired it and still had trouble. Leo says that indicates an issue with her ISP. It doesn't help that 40% of all internet traffic after 6pm tends to be streaming video traffic. That can cause a lot of buffering since there's only so much bandwidth.
There are some things Joanna can do, though. Getting a better router can help. Moving the router around may help for Wi-Fi, too. If it's bandwidth, then it's up to the cable company, and it'll likely try to upsell her to the next package. The cable company doesn't want her to stream as much as she wants.