I have a house that fights my WiFi, so I have installed a Google Nest mesh with one router and three points. It seems to me, however that all the points are connecting to the router and not to each other so the point that is furthest away from the router always has very poor connection. To counter this I have installed a second router with wired Ethernet connection to my primary router and placed close to the furthest point. The router (second) seems to wotk fine and comes up with Great and wired connection, but it has had no effect on the quality of connection on my weakly connected point. So I'm thinking it has not connected automatically to the second router. Is there a way for me to check this and/or to force it to connect to the much closer router?
Ok, there are a couple things going on here. First, the 802.11s mesh path selection policy prefers fewest hops. So, a distant mesh point that can connect directly to the primary will – even if that connection isn't particularly strong. This is usually the best policy, though, since there's only one 5GHz channel used for the mesh interconnect, so going through another intermediate mesh point would result in the data being transmitted on that channel twice instead of once. There may be some conditions under which that might be faster, but the mesh protocol can't automatically determine when it would or wouldn't make sense. Hence the default policy of just using the fewest hops. This is why the placement advice is to have the primary as close to the center of your home as possible with mesh points one or two rooms away from there – close enough that they can get strong 5GHz connections for themselves, and then provide 2.4GHz and 5GHz coverage to more distant clients. In short, don't put a mesh secondary in a spot where clients are already struggling to get coverage. They'll all connect to the strong nearby mesh point, but that mesh point won't be able to carry their traffic effectively.
The second thing going on here is that when you wire up a secondary (either another Nest WiFi Router unit or a Google WiFi unit) back to the primary's LAN port via Ethernet (either directly, or through a switched network), that secondary's traffic will be going through Ethernet instead of the 802.11s mesh. But, since the 802.11s mesh protocol doesn't run over Ethernet (it only runs over WiFi), wiring a secondary would introduce a "loop" in the network. That loop would result in some traffic flowing around and around forever. To break this loop, they use the Spanning Tree Protocol, which will stop the wired secondary from seeing the mesh interconnect. In short, wired secondaries can't act like remote base stations for more distant mesh-only secondaries. Wiring secondaries works great, but you will need to follow the placement advice for any mesh-only secondaries as if the wired secondaries weren't there.
I hope this helps explains some of the behind-the-scenes behavior you are seeing.
Many thanks for a very concise explanaition. I bit disheartening though.....
My core problem is that I cannot place the primary hub ,ore centrally than it already is and I have a couple of fixed WiFi devices (outdoor cameras) that need a strong secondary to stay on-line when I need them. I thought that my solution of placing a wired secondary close to these cameras would do the trick, but I understand now that this was the wrong way to go. I had a vison of mesh-points spread out through the house dynaically find the optimal way to exist in a network and then of clients accessing/roaming this "carpet" of mesh-points wherever it was optimal. I understand now (?) that the mesh network is really a two-teir star-network with a primary and surrounding secondaries and where the central primary needs to as central as physically possible. The second wired router which I thought of as a kind of back-haul node really can't be a part of the mesh except as another second teir point.
Is this a correct visualization?
If so is there a way of forcing a third layer of points (or in my case a single point) for that one very inaccessible part og my house/yard?
A wired secondary near those cameras should work just fine. It just can't relay traffic from more distant wireless/mesh secondaries. If those cameras are still struggling, I would check to see which access point they are actually connected to. That's a decision that clients make for themselves, but fixed devices may get "stuck" to an access point that still "works", even if a better one is nearby. Rebooting the camera may help, though a full reset may also be worth a try.
The mesh isn't actually a star network. It's just that since most traffic is destined to (or from) the internet, the primary point is the one most clients need to get to, and the "fewest hops" policy results in a star-like topology. But, if two clients wanted to talk to each other, and they were on different mesh points, and those mesh points were near each other, their traffic would go directly between those two mesh points because that's the fewest hops path. It wouldn't need to go all the way to the primary and back out.
If you're really trying to cover the largest area possible, I would focus on wired secondaries placed optimally for the clients in each area. The wireless mesh secondaries should be near the primary for optimal performance.