For all practical purposes, home networks today use only two networking technologies - Ethernet (wired) and WiFi (wireless). If you buy a modern router, you're buying one that has Ethernet ports. The typical hook up is: Cable or DSL Modem --> Router's WAN Port and the router's LAN (Ethernet) port or WiFi --> Computer and Internet connected devices For some services the ISP may provide a single box that is both a modem and router. For services like Verizon's FIOS and AT&T's Uverse, that box is called a "gateway" and is a modem/router plus handles the telephone. In either case, the device should have at least one LAN port. If you run out of LAN ports, you need to add a "switch" to the mix. Think of a switch as being analogous to a power strip for electricity. It just gives you more space to plug things in.

I don't fully understand the question, still I offer the following. If you want to install and interconnect two computers via the Ethernet Port you'll need only a CAT5 cable with RJ45 male terminations. This will allow the two computers to directly share files and other resources. I've never done this, but I think it works. If you want to connect three or more Computer via an Ethernet network you need an Ethernet Hub. These are very inexpensive. If you also want to connect to the Internet, then you'll need a Router instead of the Hub. That said, you have to have an interface to the ISP, which will NOT be Ethernet unless you are inside their facility and can patch a CAT5 cable into their router...I say this in "jest", but I read you question to say you don't understand the basics of connecting to an ISP, which has Ethernet involved only if you want to operate an Ethernet network inside your home/business. Now backing off in ignorance, I admit if you have Fiber Optical cable to your home/business, that my have an Ethernet interface... don't know.

Are you sure you really need a gigabit connection from your house to your workshop? The gigabit connection does nothing for your internet connection and is only useful for very high speed data transfers on computers or NAS within your LAN. Are you using equipment with true gigabit ports and performance on them? Do you really need that kind of LAN speed? If not, just break out an unused 10/100 pair from the CAT6 before the terminating connector at each end to use for your POTS. By definition, any VOIP adapter whether LAN or WAN is no longer POTS and will require an active network. While it's possible to design a low pass/high pass filter to separate the two, the same as is used for DSL delivered over phone lines to the house, it will inherently drop your speed back down to a 10/100 Mbps LAN.

While it works best to have your modem, router, and patch panel all centrally located, if it helps solve your current problem, the modem could be "virtually located" in the mechanical room. In other words, if the modem is currently being fed it's signal in a particular room, and that room has a network jack, you could then send the internet connection down to the mechanical room and to the router. While you are not splitting the signal, in the traditional sense, and it does not weaken, you still have some limitations. The output from the modem goes into the router. The router then acts like a "traffic cop" directing information from the modem, to-and-from the individual ports on the router. The modem has an IP (internet protocol) address assigned to it from your ISP (internet service provider). The router then assigns IP addresses to each device connected to it, and carefully routes data from each port's address through the main IP address and back again - all using just a single connection. The limitation is in how much data each connected device is downloading, or uploading. I'm in a rural area with DSL that has about 1.5 Mbs download speed. To stream something like Netflix in standard definition, that connection speed is about the minimum you can get away with. Can two people watch two separate streams? No. Can four people browse the internet? Sure. We have three computers normally on-line, home security cameras, internet radio streaming and some misc equipment - and no problems. Download and upload speeds for residential service is almost always asynchronous, meaning you can usually only upload at a fraction of your download speed. This usually works well, since that's the way we normally use the internet. However, if you have something like home security cameras that can be viewed over the internet, you going to be uploading a lot of data and possibly slowing traffic on the download side of your internet connection. So, again the limitation is in the amount of data being received and sent. As a matter of fact, most 4 port routers usually allow a second router to daisy chain to it and create additional ports.