Everybody like the idea of mesh but you need to understand that mesh is for coverage only but not speed.

Say you have one router station at A. Then you find that at location B your signal is weak and can get only 1Mbps. Then you put a mesh router at B to get strong signal. Yes your signal is going to be strong there BUT if you mesh router at B is relying on wireless connection to A then the max speed you can get in B is just the max link connection between router A and router B. If the connection is at 1Mbps, your strong signal at B can only deliver 1MBps max. Therefore, for best throughput, you would need a cabled link between the router A and the router B.

The main purpose of mesh id that you do not need to switch to another router when you roam from one node to another node. You also get better coverage but the speed depends on how you link between your mesh router. If you plan to connect them wirelessly, you can get higher speed if your mesh routers are close to each other but that would beat the purpose

It would be no different I'd say. If dedicated mesh uses own custom protocol to signal each other then you have no other option but to use router from same manufacturer. I would go for EasyMesy and I think every manufacturer will eventually go for open system because that is what people want.

I bought Asus last time because it can be used with different Asus models, more flexible than router that comes in a set like Deco. I thought I will add one more later to cover upstairs but end up I can just use one at the living hall to cover whole house. I think the most you need is just 2 routers for 2 storey house. Probably no need to use extender.

The main problem to WiFi probably more on interference than the brick wall or wooden door. So, depends on house layout probably. With only 1 wireless AP I can cover my whole house of about 3000+ sqft with no problem.. Even on 5GHz band it still managed to to deliver speed of at least about 200Mbps anywhere in the house.

I've never heard about limit of mesh of just only 5 nodes wired. That is probably that particular brand firmware with star distribution to 5 mesh nodes. Theoretically is can go much higher. Even in theory one router can go 255 clients but in reality you will have sluggish connection. This due to the way WiFI operates. As you know WIFI is just simplex communication. A router can only transmit or receive at any given time and only can handle 1 client at a time. When many (or even two) clients try to talk to router at the same time, only one can get through. Thus the rest have to wait for turn but the problem is the wait time is just random, not first come first served.

I think the Deco mesh if connect wirelessly is not efficient because The mesh communication and users transmission shares the same band. Therefore, you will have more data collisions. It will significantly slow down connection where many use the network. Home grade WiFi router can slow down with just probably around 6 to 8 clients although theoretically can serve 255 clients

That is why big companies uses enterprise solution to manage mesh routers. Maybe this article will helps your project.

https://commotionwireless.net/docs/cck/netw...lines-for-mesh/