deco x60

Model: Deco X60 I know this issue has been raised many times but I haven't seen a solution. Room 1 - The main deco which is connected to the router. Room 2 - The middle room Room 3 - The furthest. Why does the Deco from Room 3 use the Room 1 Deco as a source rather than Room 2's? Decos only use...