Mike is frustrated that his internet access is going through a lot of buffering, especially when he's streaming. Leo says a router needs to control his ethernet connection, not a modem. It's the one assigning IP addresses. Then he can put routers all over the house, but have them set in bridge mode so that they just pass the bandwidth along. Mike should try using different names for his routers, too. That way, he can join the nearest ones directly. Getting a mesh router is also be a good idea. They aren't cheap, but they definitely solve the problem. Leo recommends the Eeros. They work with wired connections.
(Disclaimer: Eero is a sponsor)