Connecting two PCs via LAN cable

Charles Thompson15 said:Sure, UTP runs between the router and the computer, but that’s not really what we’re getting at here. We're talking about the connection between the router and the line coming from the utility pole where I'm tapping in up in the attic. An RJ11 cable plugs directly into the DSL port on the router.

So, what’s the actual issue? Almost every ADSL setup out there uses standard telephone wiring—you know, those basic two-wire pairs.
As long as the wire isn't physically trashed, you're fine. It's easy to extend; just strip the ends, twist them together, and wrap them tight with some electrical tape.
The wires inside the cable are symmetrical, so honestly, it doesn't even matter which one you pair with which.

I don't know what kind of speeds you're dreaming of, but for 25Mb/s, a standard phone line shouldn't be an issue.

A basic CAT3 phone cable works just fine, though you’d probably get better results using some upgraded blue and white twisted pair 😁
I actually used a 20m flat, flexible 4x0.3 phone cable for years. Once my kids moved out, I swapped the router from their room over to the hallway near the jack, and honestly, it didn't change a thing regarding the DSL speeds. Later on, I just crimped an RJ45 onto that same cable, and now it works perfectly as a 100Mbps LAN connection for the PC in that room.

Charles Thompson15 said:Sure, UTP runs between the router and the computer, but that’s not really what we’re getting at here. We're talking about the connection between the router and the line coming from the utility pole where I'm tapping in up in the attic. An RJ11 cable plugs directly into the DSL port on the router.

I guess on some routers, that DSL port can actually be an RJ45...

So, we went ahead and did it. We ran a new phone line, but the technicians are insisting it's just a standard thin phone wire. They’re claiming I really need to be using a 0.5 or 0.6mm UTP cable—specifically Cat7 or Cat8—for the run from the attic to the router.
I picked up a cable that already has RJ45 connectors on it, but then I noticed the port on my router is actually an RJ11 slot. It looks like I'll have to crimp new RJ11 connectors onto the cable, join the wires, and then just splice the other end in the attic and tape it off.
The plan is this: once I swap out that new phone line (which was only installed six months ago!) for the UTP cable, if the connection still acts up, they'll have to look at replacing the actual line coming from the utility pole to the house.

My contract is for 50 Mb/s, but I rarely see anything close to that. Most of the time it's under 10, and occasionally it even dips below 5 Mb/s or just drops out entirely.

Charles Thompson15 said:So, we went ahead and did it. We ran a new phone line, but the technicians are insisting it's just a standard thin phone wire. They’re claiming I really need to be using a 0.5 or 0.6mm UTP cable—specifically Cat7 or Cat8—for the run from the attic to the router.
I picked up a cable that already has RJ45 connectors on it, but then I noticed the port on my router is actually an RJ11 slot. It looks like I'll have to crimp new RJ11 connectors onto the cable, join the wires, and then just splice the other end in the attic and tape it off.
The plan is this: once I swap out that new phone line (which was only installed six months ago!) for the UTP cable, if the connection still acts up, they'll have to look at replacing the actual line coming from the utility pole to the house.

My contract is for 50 Mb/s, but I rarely see anything close to that. Most of the time it's under 10, and occasionally it even dips below 5 Mb/s or just drops out entirely.

the technician's logic
so their miles of wiring are perfect, but your five measly feet is where the problem lies. classic.

It’s usually on them, but you're the one who has to play detective and prove it.

One way to handle it? Put the router right up in the attic, directly on their line, and then just run a 5 or 10m UTP cable from the computer to the router up there.
If the connection still sucks after that, you've effectively proven the attic isn't the issue—it's their incoming line.

And when you move the router up there, you can just use your phone via Wi-Fi to run speed tests.

I don't actually use UTP to connect my router to my computer; everything runs over Wi-Fi.

That’s technically an option, sure, but I'd end up with zero signal on the ground floor.

So, the bottom line is that the current standard phone line can stay as it is. The technicians were just pushing me to install UTP so they could rule out any possibility of the issue being on my end.

Charles Thompson15 said:I don't actually use UTP to connect my router to my computer; everything runs over Wi-Fi.

That’s technically an option, sure, but I'd end up with zero signal on the ground floor.

So, the bottom line is that the current standard phone line can stay as it is. The technicians were just pushing me to install UTP so they could rule out any possibility of the issue being on my end.

here’s how I see it
putting the router in the attic is strictly for TESTING—just to prove the house wiring isn't the culprit by plugging directly into the AT&T drop.

Even though they checked everything from my device all the way to the router, up to the attic, and even out to the terminal on the pole, about six months ago they concluded that any signal loss between the terminal and the attic was negligible. They blamed the router connection instead, specifically the line running from the attic to the router, which was using an old cable. So, we replaced it with a new phone line. But when the technicians came back recently because of the drops and slow speeds, it turned out the issue was actually at the terminal. They ended up switching me over to a different terminal and told us we used the wrong cable—that we should be using specific UTP Cat5e.

Honestly, I’m just going to leave it as it is. If the issues persist—and they already are, since the connection is slow even if it isn't dropping entirely—I'll just call them back and let them deal with fixing their own AT&T cabling.