Xfinity disrupting (whole court) bandwidth for graphics

I discovered that advertising (such as 'trial subscriptions') could be reducing performance on our family wireless subscription (some Mac-based and some-Windows 7-professional(s)/10); and computer (in-home) network for items like "xfinity" games (which we do not use).  How can we get more consistent performance for our family-plan, AT&T?

E-Liz (Virginia)