Here is my set-up:
I recently cancelled my DirecTV satellite service to go with LIVE TV streaming because it is so much cheaper long-term. My main Orbi router is in the center of the house (living room) and I have 2 satellites, 1 placed at the back end of the house and 1 at the front end of the house. Distance wise...the one at the back end is roughly 10ft from the main router through a wall. The one at the front end is roughly 20ft from the main router through several walls. I'm getting occasional buffering with our TV's next to the satellites that are running the firesticks. As far as videos on our phones/tablets we don't get any buffering. I'm not sure what to look for or what I need to do to determine what the issue might be. I figured the internet speed + the mesh network would be plenty to support.