If the connection to your home is the Last Mile, the connections inside your home can be called the Last 100 Feet. At the birth of broadband Internet, the connection to individual computers was always wired. I made sure there was an Ethernet jack in my guest bedroom in my home at the time for visiting technical friends. Fortunately, we have WiFI and other options now to let us use our devices without having to tie them to a wall jack.
The first connection is still the best: if you can, use wired Ethernet. Each computer is independent and does not share bandwidth with any others, at least not until it connects to the rest of the home network. All home Internet routers seem to use the same class of network chips because they all have four LAN ports on them. You can connect more than four devices by adding an Ethernet Switch. Just connect a wire from one of the LAN ports on the router to one of the ports on the switch. You can even connect switches to switches, although there is a limit of how many switches can be connected in a line between two systems. Switches are called switches because they behave as switches, connecting the device that is sending to the device that is receiving, as the information is flowing.
The Multimedia over Coax Alliance established standards for MoCA devices that let you use cable TV or satellite TV coax cable already in your house for wired connections. If you use the same coax used for cable or satellite, you have to have the MoCA devices configured to work with the service you have and you have to make sure you block the signal from leavingyour house. MoCA signals will pass backwards, forwards, and from port to port on coax splitters. I have never used it on a live cable or satellite system, but I have used a pair of MoCA adapters on an isolated coax run from one room to another in a home. MoCA is not as fast as the fastest Ethernet, but it is a wired connection.
Most people use WiFi, to the point that "WiFi" is synonymous with "Internet" in many minds -- and more than one software package conflates them, too. When you get a broadband connection, the provider usually gives you a device that combines a connection to their last mile, a router, a switch (4 ports external!), and a WiFi "access point". Most people connect their laptop, printer, and phone to the WiFi network and it becomes "the Internet" for them. If your house is too large or the walls block radio signals, you can use one of several WiFi schemes that increase the coverage area. Several companies sell "mesh" systems that put multiple access points in your home, all connected with wires or by relaying traffic over WiFi connections to another device in the mesh. There are also "extenders" and you an use multiple, independent access points.