The key with wiring is - the “twisted pairs” are the color-coded pairs that are wrapped around each other. Ethernet typically uses 1-2 and 3-6. There are super-high-speed schemes I understand that use more. But for you and I - 1-2, 3-6. (One pair is transmit +/-, the other receive +/-) I even once made a splitter box pair that used 4-5 and 7-8 at both ends so I could run 2 ethernet drops on one cable. The “standard” colours are just to ensure that nobody gets confused. Beyond a certain distance, if the +/- are not twisted around each other, the signal does not travel well. As I mentioned, I saw this problem manifest at about 50 feet.
(You will find odd cables that are straight thru for non-ethernet purposes 12345678 - typically these the individual wires are 8 colors, not ethernet’s blue-green-brown-orange, color matched with color-white. there are also crossover cables, where 1-2 goes to 4-5 on the other end and vice-versa. Often these cables are red. They were to connect two switches (transmit on switch is receive on the PC or other device, but switch to switch reversing transmit and receive was needed) but nowadays most devices are smart enough to adapt to what’s on the other end and standard ethernet is all you need.
I guess it the very early days, someone said. "hey - you can use the same wiring for phone and ethernet. Make 4-5 the live phone line, and your RJ-11 phone plug will work in the same socket, so in your office you can use that wall socket for phone or ethernet. But… I never saw this implemented in real life. Most office phones quickly became fancy affairs with multiple lines, and special buttons, needing their own dedicated wiring or coexisting on ethernet as VoIP.
If you can’t get a signal 120 feet over the cable, even with Cat 5, double check your cable punch-downs. I have had erratic luck putting on those clear plastic (“Crystal”) ends, but with socket punch-downs, if done with the right tool, they should be foolproof. Something is wrong. Next I would suspect crimped or broken wiring. (It goes without saying, don’t use a high-powered stapler to tack down ethernet. The pro installers I’ve seen have either screw-down or peel and stick loops where they can tied down the cable with tie-wraps)
There are some not-too-expensive ethernet cable testers on Amazon.
if you are spending good money on a full rewire job, I would go Cat 6 just for future-proofing. (If you are redoing the drywall and I assume the electrical, the cost difference for top-end ethernet should be minimal) Also note that the sockets, patch cables, etc. come in CAT5, CAT5e and Cat6 so be sure to get the right terminations too. For longer runs, you might also consider running 2 cables, even if you only terminate one and leave the other in the wall. An earlier incarnation of TV service preferred a direct run from the main TV box to each TV - otherwise it would overload the network and slow traffic. I would also seriously consider a separate wiring for PoE/IP security cameras to their DVR. There are plate fittings where the faceplate can be attached to this minimal bendable metal frame, instead of a full metal electrical outlet box - but with many new devices (such as security cameras) using PoE, some code may now require PoE to be terminated in a grounded box, and surface runs in conduit. In fact, may apply to all new ethernet installs, in case the run is later used for PoE - check your local electrical code. separation from 120V is certainly something to pay attention to. Several provinces in Canada require ethernet commercial installs to be done by a qualified electrician.
Also consider that you may need to plug in the device that uses the ethernet so locate it near a power plug. One of best choices I made when building my house 14 years ago was to also put a drop wherever a TV would go, as well as in each room. I now have 5 switches, almost all full, and it’s scary how many wired and wifi devices are listed on my router. 2 printers, 3 PC’s (including the XP one), 2Mac minis and a Macbook Air, 4 virtual PC’s, Apple TV, 2 smart TV’s, Nest thermostat, Airport and the Control4 and audio distribution system it’s connected to, 2 stereo amps, a cable box router and 3 distribution TV boxes, not to mention 2 iPhones and 3 old iPhones that I power on and charge monthly.4 iPads, 3 apple watches, a new Paperwhite Kindle and an original Kindle that no longer connects on WiFI, and a Samsung tablet, an old Wii and Reolink security camera. Oh, and my Tesla connects to the WiFi when parked. Just imagine when you appliances start connecting. And that’s just for my wife and I…
I have too much shit.