The use of switches (network switches) is currently the prerogative of company networks in particular, but they are also used in home networks. In the market you will find switches in various price categories, which differ in parameters and additional functions. What to focus on and how to choose a new switch? This is the issue to what we will apply in the following lines.
When you have a fast connection, but there are significant speed fluctuations, something is probably wrong. It is a question, where to start looking. Basically, you should first verify if the connection really offers the speed which you have agreed with the provider in the contract. The problems can also be caused by a large number of running applications, it is necessary to check it and possibly leave only those one that you are currently using. Then check the aggregation and after that the router.
Are you asking what the point is to connect two routers? Their connection can be very beneficial and has several possibilities how to use them. Do you want to create a network that reliably covers the whole house? Then the connected routers are the optimal solution. Do you need to extend the range of Wi-Fi so that you can easily have a wireless signal available in the workshop, garage or in the yard or other areas? Connecting routers will allow you to do that.
We will definitely not start building a house blindly, without a project and consultation with experts. Even so, you have to keep in mind the data wiring, without which some modern house or other building can't get by today. You will certainly want to use an intelligent operation control for your new home, and data wiring (together with antenna and other distribution) is undoubtedly needed for this function.