RJ11 cables and their effect on Speed and Dropouts
Posted: Wed Jul 17, 2019 5:54 pm
I have a Billion 8800NL R2 used as a modem (bridge mode for FTTC connection) absolutely no problems with this over the last five months since install.
I have read a lot about R11 cables (socket to modem/router) length, twisted wires or not gold contacts etc.
Initially (with some experience of both IT and electronics) I totally dismissed the fact that a short RJ11 cable between the face plate and the modem would make any difference at all to speed or reliability. Why should it when the green cabinet was 500m away and joined to the house with unscreened twisted pairs all bundled together then untwisted cable for 20m from the pole to the house.
Although a better cable may not be the solution a problem with "upload" not so much with download made me think again. Download was and is fairly steady around 38 Mbit/sec. Upload was nearly ten, dropped to 8 ish and then dropped to 0.9 .
Nothing had changed or so I thought. Then when the ISP added comments to my ticket I saw ...
"Interference Pattern Regular Interference Observed Daily" but qualified with "SERVICE IMPACT.... No impact observed" (ok maybe means line didn't drop)
Then the penny dropped....
A. I have lots of RJ11 cables and you can't see if they are made with twisted pair cable without cutting them open. None I have seen are screened.
B. This final few feet of the 500m connection from the green box runs past mains wires, the DECT phone, LED lights, other equipment with WiFi like the printer etc. etc. Plus PCs with their lousy switching mode power supplies. LED lights are low voltage dc right? Yes, but how do we get this from 230v ac? Via a cheap noisy power supply and this noise is probably transferred on the long wires to led strip itself.
C. In all the RJ11 is likely close to any number of other things too, microwave, central heating pump and thermostat and so on.
There are different kinds of electrical noise (one-off spikes {the central heating thermostat}, and constant noise {power supplies} and something in between like the microwave and vacuum cleaner) and it is mostly in your home and almost certainly close to the phone line, I don't have phone extension sockets but a lot of people do, so add this to the list even if the old bell wire is disconnected. This long bell wire acted like an aerial picking up noise.
Cutting open a spare RJ11 cable I found it used just straight wires not twisted. Two things in a cable design {ok probably more} help reduce the noise picked up, twisting the wires and screening {like cat-6 cable is I'm told}. Making the cable as short as possible helps too. OK radio fanatics will dispute this based on half wavelengths or something (only kidding) .
Conclusion?
There is potential a lot of electrical interference close to the RJ11 cable from socket to modem/router.
I moved the DECT phone, turned off the LED lights, moved the Billion to within a foot of the wall socket, and coiled the RJ11 cable (will make a new cable instead of using a supplied one when my RJ11 plugs arrived tomorrow) Result, upload remains at 8.4 (it suddenly hit 8.4 after being 0.9 a couple of hours ago) download is 39.x almost 2 Mbps faster than I have had for months.
If upload remains at 8.x by tomorrow then I can reasonably assume that interference was the problem. This will confirm if twisted pair and a short cable really do make a difference. I don't think that gold contacts make much difference, just use contact cleaner and/or unplug and plug in again once a year.
Should you pay a fortune for a special RJ11 ultra-fast cable? Regardless of the outcome of my experiments NO ! The problem with advertised cables is that they don't tell you what the actual spec is (like twisted cables or not) and I have not seen a screened one as yet. I don't know the spec of the cable supplied with the Billion, it's lost in my pile of cables in the draw.
I plan to make a new RJ11 cable from two connectors costing pennies and a piece of Cat-5e cable I have, this will be a foot or less long as the modem will sit right by the socket. Once I have a piece of screened cable I will make another and see if this makes any further difference, just remember to ground the screen (ok what to?) at one end only.
More info as I get some results or not, comments welcome, please refute anything or all of this !!
I have read a lot about R11 cables (socket to modem/router) length, twisted wires or not gold contacts etc.
Initially (with some experience of both IT and electronics) I totally dismissed the fact that a short RJ11 cable between the face plate and the modem would make any difference at all to speed or reliability. Why should it when the green cabinet was 500m away and joined to the house with unscreened twisted pairs all bundled together then untwisted cable for 20m from the pole to the house.
Although a better cable may not be the solution a problem with "upload" not so much with download made me think again. Download was and is fairly steady around 38 Mbit/sec. Upload was nearly ten, dropped to 8 ish and then dropped to 0.9 .
Nothing had changed or so I thought. Then when the ISP added comments to my ticket I saw ...
"Interference Pattern Regular Interference Observed Daily" but qualified with "SERVICE IMPACT.... No impact observed" (ok maybe means line didn't drop)
Then the penny dropped....
A. I have lots of RJ11 cables and you can't see if they are made with twisted pair cable without cutting them open. None I have seen are screened.
B. This final few feet of the 500m connection from the green box runs past mains wires, the DECT phone, LED lights, other equipment with WiFi like the printer etc. etc. Plus PCs with their lousy switching mode power supplies. LED lights are low voltage dc right? Yes, but how do we get this from 230v ac? Via a cheap noisy power supply and this noise is probably transferred on the long wires to led strip itself.
C. In all the RJ11 is likely close to any number of other things too, microwave, central heating pump and thermostat and so on.
There are different kinds of electrical noise (one-off spikes {the central heating thermostat}, and constant noise {power supplies} and something in between like the microwave and vacuum cleaner) and it is mostly in your home and almost certainly close to the phone line, I don't have phone extension sockets but a lot of people do, so add this to the list even if the old bell wire is disconnected. This long bell wire acted like an aerial picking up noise.
Cutting open a spare RJ11 cable I found it used just straight wires not twisted. Two things in a cable design {ok probably more} help reduce the noise picked up, twisting the wires and screening {like cat-6 cable is I'm told}. Making the cable as short as possible helps too. OK radio fanatics will dispute this based on half wavelengths or something (only kidding) .
Conclusion?
There is potential a lot of electrical interference close to the RJ11 cable from socket to modem/router.
I moved the DECT phone, turned off the LED lights, moved the Billion to within a foot of the wall socket, and coiled the RJ11 cable (will make a new cable instead of using a supplied one when my RJ11 plugs arrived tomorrow) Result, upload remains at 8.4 (it suddenly hit 8.4 after being 0.9 a couple of hours ago) download is 39.x almost 2 Mbps faster than I have had for months.
If upload remains at 8.x by tomorrow then I can reasonably assume that interference was the problem. This will confirm if twisted pair and a short cable really do make a difference. I don't think that gold contacts make much difference, just use contact cleaner and/or unplug and plug in again once a year.
Should you pay a fortune for a special RJ11 ultra-fast cable? Regardless of the outcome of my experiments NO ! The problem with advertised cables is that they don't tell you what the actual spec is (like twisted cables or not) and I have not seen a screened one as yet. I don't know the spec of the cable supplied with the Billion, it's lost in my pile of cables in the draw.
I plan to make a new RJ11 cable from two connectors costing pennies and a piece of Cat-5e cable I have, this will be a foot or less long as the modem will sit right by the socket. Once I have a piece of screened cable I will make another and see if this makes any further difference, just remember to ground the screen (ok what to?) at one end only.
More info as I get some results or not, comments welcome, please refute anything or all of this !!