Homemade Wifi Mesh Tutorial

Hi, so today I have been attempting to solve wifi dead zones in the house. I came across this tutorial on wifi mesh / extension of wifi.

In summary, I have connected a router with another router.

I will name the first router the main router and the extended router the secondary router.

The main router will have the gateway IP of 192.168.1.254
The secondary router will have the gateway IP of 192.168.1.2

In addition to the routers, I have deployed a wireless extender with the gateway IP of 192.168.1.5
This wireless extender is an extension to the secondary router.

Sounds complicated?
Here is a diagram of the whole system