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Last year I built my house and I have lots of conduit and wiring throughout. Everything works great except for one nagging issue.

My DSL router's connection seems to degrade over time. It gets to the point (after several months) where it can't even keep a connection to the PPP server. At that point if I cut off the phone cable ends and put new ones on it works fine again for another few months.

I have CAT 5 wire running to the phone box on the side of my house. I use two of the CAT 5 wires which run through the whole length of my house to the model. I have a RJ-11 coming off those two wires which plug into my router/modem.

We don't have phone service, just DSL so there are no filters.

Should I rerun the line from the phone box to my modem with higher gauge wire?

Any other ideas?

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24 awg should suffice, it is the same gauge that carries the signal in the CO. You might rather look at getting higher grade copper instead, or better RJ-11 plugs. Another thing to look at would be your crimping method, do you crimp it with the a portion of the casing in the plug, or do you leave some exposed wire? Do you crimp twice to ensure a strong crimp? Do you secure the cable in any way after crimping and if so, with what method? Have you measured the DB loss on the cable? What pair on the cat5e cable are you using? How many termination points from the phone box to the modem/router? –  MaQleod Oct 3 '11 at 21:31
I have a really nice ideal crimping tool and I don't expose the wire. It is a very strong crimp since it ratchets down. I just redid the connection today and I have pretty good numbers on the cable, but I'll check that if/when it starts going bad again. –  Bryant Oct 3 '11 at 22:21
Phone lines should not run on CAT5 - Twisted pairs cause interference that causes performance issues on ADSL/DSL frequencies.(even though builder say its ok) twisted pair for voice is ok but on ADLS it causes electro magnetic resonance and if you go flat>twisted>flat.. you going to have performance issues.I have seend wires rusted and drenched in water, in an absolute state- and they work fine. something else is wrong in your installation. –  ppumkin Oct 4 '11 at 12:58
It doesn't go Flat>twisted>Flat, just Flat>twisted. I tested the noise at both the box and at my router location inside the house and the noise level is the same. So I think the CAT5 seems to be just fine. –  Bryant Oct 4 '11 at 16:00
Go to an auto parts place and get some "high voltage" clear silicone grease. This is intended for distributor caps. Put a tiny dab on the end of the cut cable before you crimp on the ends, and then put a tiny dab on the connector contacts before plugging in. (And, no, the grease DOES NOT prevent the connectors from making good contact -- quite the opposite.) –  Daniel R Hicks Dec 25 '13 at 2:57
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4 Answers

It sounds like water may be getting into your RJ-11 jack somewhere, probably outside where it comes into the house. AFAIK CAT-5/5e/6 all use a specific gauge wire and the TX/RX power levels of equipment is calibrated to that size of wire, the difference is the number of twists per foot. Home Depot/Lowes usually sell some waterproof "grease" for sealing cable splices underground and outside in their wiring section, taking some of that and filling the small cavity of the RJ-11 connector outside would probably help to keep the moisture out. I'd try that before pulling heavier gauge wire that will probably experience the same issue over time.

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a DSL signal doesn't care about twists per foot, it could be untwisted pair and will act the same. There really is no evidence to assume it is anything to do with water. The power levels have nothing to do with gauge, but a higher gauge will be a little less prone to margin issues (signal to noise ratio), though on such a short cable, it will likely be inconsequential, but couldn't hurt. The primary cause for these types of issues, in my experience anyway, is either a bad crimp or a badly secured cable (staples are a horrible method for example). –  MaQleod Oct 3 '11 at 21:42
The box is sealed and build into the wall of the house, so there are no water issues. –  Bryant Oct 3 '11 at 22:19
The reason I suspect that it may be water is because of the phrase "degrade over time". To me this sounds like some sort of corrosion that is happening due to my assumption that when you fix the connectors it's working fine for a while and then starts to degrade. To me, cable of the incorrect size would be immediately apparent rather than a degradation over time. I know that DSL doesn't care about twists per foot, I was just stating that the gauge of wire was the same regardless of cable spec. –  d34dh0r53 Oct 5 '11 at 19:10
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up vote 3 down vote accepted

While doing some more research I came across this article on DSL wiring issues. The key part of the article for my case was the Signal to Noise Ratio (SNR):

Signal-to-noise ratio (SNR) is another figure you can find in your ADSL stats of your home / corporate router (show dsl interface atm(something) for Cisco). This number also expressed in dBs and describes the relation between your speaking strength (signal) and street’s noise strength (noise). The higher this number the better since your voice outperforms the noise.

  • 10dB and below is bad
  • 11db – 20dB is OK
  • 20dB – 28dB is excellent
  • 29dB and above is outstanding

I started to monitor my SNR and saw that when the connection started dropping the SNR was dropping below 8dB right before. I tested hooking the router up directly to the phone line box and found my SNR to be 18.1dB without the line in the house.

While testing the outside connection I did see it drop by 2dB at one point and figured out that it was due to me putting my laptop next to the phone cable. That made me realize how sensitive the line was to noise.

Armed with this information I headed up to my wiring closet and did a few things:

  • Wrapped the wire that was not wrapped in the CAT5 sheath with electrical tape
  • Mounted the router on the wall of the closet instead of having it sitting on a server
  • Made sure all the extra cable going to the router was hung up and away from any power cords

Having done all this the SNR is 18dB (down 0.1dB from outside) which is great. So thanks to MaQleod for stating the wire gauge shouldn't be the issue since that started me on the right track. Thanks for the other answers which also seem to point to noise being the issue, but it wasn't water, fumes, or the termination (good ideas though).

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Don't forget to accept this answer when you can, if it solved your problem! –  AndrejaKo Oct 4 '11 at 17:15
Can accept your own answer for 24 hours.... –  Bryant Oct 4 '11 at 17:16
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Since re-terminating fixes the problem temporarily, the problem is most likely termination.

You are probably crimping a 6P2C modular connector (RJ11) rather than a 8P8C modular connector (RJ45) so there is some possibility of using connectors that are designed for different cable.

Stranded wire used in Cat5 patch cables requires different connectors than those for solid wire used in Cat5 cabling installed into conduits.

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Termination was fine. Turned out it was just interference and so moving the wires to re-terminate solved it temporarily. –  Bryant Oct 4 '11 at 15:58
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Either get better quality/correct (stranded vs solid, eg) terminations or work some "high voltage grease" (silicone grease in a small tube, available from an auto parts place) into the connection -- probably coat the wire and inside of the connector heavily with it before termination if using crimp-ons.

And check your furnace, water heater, and other "combustion appliances" -- a likely cause of this problem is fumes in the house. (Another likely cause is Chinese drywall.)

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Fumes causing noise on a wire? Not sure I follow this idea. We don't have chinese drywall, we built our own house. :) –  Bryant Oct 4 '11 at 15:59
Various types of fumes can cause corrosion in electrical connections. The Chinese drywall caused electrical fires in some cases, due to corrosion. –  Daniel R Hicks Oct 5 '11 at 3:17
Interesting. However, I suspect that it would take quite awhile for the fumes to corrupt electrical cables. –  Bryant Oct 5 '11 at 14:53
A few weeks, probably, if the fumes are strong enough, but in the fire cases likely a few months. It doesn't degrade the insulation, it causes the connections to corrode. –  Daniel R Hicks Oct 5 '11 at 19:42
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