I basically have an ethernet cord ran under my house from my router to my PC. I also use another ethernet cord and connect the two via a connector to plug it into my Xbox 360. However, the problem is I can only use one at a time; my PC or my 360. Now, is there a way to use a splitter like these; http://www.pccables.com/02235.html?gclid=CI7h2OHJ-7gCFbCDQgodqSoAdw and http://www.bhphotovideo.com/bnh/controller/home?O=&sku=961428&is=REG&Q=&A=details ?
I read that these wouldn't work properly because of the TCP/IP protocols.
I've enclosed a diagram illustrating my current situation. If a splitter wouldn't work, what would be the best way to have them both connected simultaneously without having to run another cable under the house?
No a splitter will not work.
What you want is a network switch. You plug the cable that runs under the house from the router into one of the switch ports. Then you use two of the other switch ports to run cables to the Xbox and PC. The switch with the work with the router to had the TCP/IP part of things.
This is what I use for a similar type purpose (my cable is not 50 ft...more like 15 feet at most):http://www.newegg.com/Product/Product.aspx?Item=N82E16833122128
(I actually currently use the 8 port version, but had a 5 port in the past that my dad is currently using for a similar purpose)
There are other cheaper options, especially if you do not need Gigabit ports...the above is meant to be an example.
FWIW, a typical router is a combination of at least three different pieces of hardware: 1) an NAT router; 2) a WiFi access point; and 3) a network switch. When broadband routers originally came out (more than a decade ago), they typically did have the later two parts included. As result, there would only be ONE LAN port on a router even though the router would technically allow you to hook up more than one computer...just not physically. You typically then need to buy a switch or a hub to have more than one computer hooked up to the router. Initially the router was there to simply act as a firewall for that one computer. Fairly quickly, however, they started selling routers that included switches with several ports...thus physically allowing multiple computer to router. It was not until several years later that routers would start to also including WiFi access points.
I mention this to illustrate that you already have one switch on your network...the one built into your router. You can use additional switches to effectively add more ports to your network/router if you even run out of ports on your router (this is the other reason I use a switch).