Advice welcomed: am I trying the correct cable?

[#1]

I have a Hub 2 router connected to a BT Mk4 wall box by a short cable. I'd like to move the router further away (approximately 6m) and so I purchased what was advertised as a modem cable.

When I replaced the original cable with the new one and switched the router back on, its lights flashed and it wouldn't stabilise. Checking on a PC, the report was that the connection was faulty.

When I put the original cable back, everything was fine again.

Is it significant that the plugs on the original cable appear to have only two contacts, while the new ones have four?

Also the new plugs are significantly smaller than the socket on the router and (especially) the socket on the BT box (the correct socket: I didn't use the phone socket by mistake). Are those factors enough to cause the connection problem? Googling suggests that the sockets on the BT box and the Hub 2 are both RJ11, and that a "modem cable" uses RJ11 plugs.

I'd be very grateful for any thoughts. Many thanks.

[#2]

Have I posted this in the wrong section? Would "My router" be more appropriate? Apologies, if so.

[#3]

Moderator's note:
Thread moved from Broadband to My Router

[#4]

Thanks for the move.

[#5]

@BertCoules 

When you use the new cable, looking at the Hub Light it is flashing orange? This would suggest the new cable is faulty or incorrect wiring..

Do not be concerned about only two pins having wires, as that is all that's needed for a xDSL signal. 

So with an RJ11 for a modem only, the plug may only have pins 3 (red) and 4 (green) connected. One pair

The cable should be 1 to 1, 2 to 2 etc with no crossovers. so the colour on each wire should be the same both ends of the cable

I have in my stock of old stuff a DSL cable which looks just like yours, pins 1 and 6 are just blanks as they are never used for phone or modem equipment. Looking into the DSL socket of the Hub there are only four pins.

RJ11 cables for phones would need at least three wires, extra wire is for the bell circuit, which would explain four wires on the new cable.

[#6]

@Dan_the_Van

Thanks for that. The Hub light was definitely flashing and I think it was orange but being colour blind I can't be absolutely sure. I suspect that the cable is faulty: I noticed that the packaging had been opened and resealed, which could well mean that it had been returned by a previous buyer and simply put back on sale. I'll return it myself and try to get another.

[#7]

@BertCoules I think @Dan_the_Van sort of beat me to it, but many cables advertised as "modem cables" are not straight through and/or don't use the "innermost" pair. You really want something specifically advertised as an ADSL cable.

Or it could be just plain faulty........ 🤣

[#8]

Well, that was interesting. I obtained a replacement cable, connected it - and got exactly the same result, a flashing, possibly orange, light on the router.  And once again, returning to the existing cable put everything right.

@HPsauce and @Dan_the_Van  Here are the two ends of the new cable. Is this wiring correct for the BT wall box to the Hub 2? The cable is labeled ADSL.

[#9]

@BertCoules 

Sorry I been side tracked today, had an electrical issue that needed resolving.

The cable look fine to me, seems odd it's not working. Is the cable being sold for use with a modem, as they should be standard.

Silly question you are pushing the plugs fully in, does it align correctly in the DSL socket on the Hub Two?

[#10]

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@Dan_the_Van wrote:

Sorry I been side tracked today, had an electrical issue that needed resolving.

The cable look fine to me, seems odd it's not working. Is the cable being sold for use with a modem, as they should be standard.

Silly question you are pushing the plugs fully in, does it align correctly in the DSL socket on the Hub Two?

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No apology necessary; I'm grateful for your help (and that of others).

The box is labeled "Modem cable : ADSL".

It's not at all a silly question: I wondered about that myself. I'm confident that I'm pushing the plugs fully home, but I'm not certain about the alignment: the plugs are noticeably smaller than the sockets in both the Hub and (especially) the BT wall box. I won't be able to try again until tomorrow, but then I'll experiment with wiggling the plugs around and see if I can get a proper contact that way.

Thanks for your thoughts.

[#11]

Hi there, I don't think its the new cable that is at fault its the actual plug on it, RJ11 plugs and sockets are specific to each other so you need a new cable with the exact plug on it as the one you are replacing, if you look closely at the DSL socket on the router and then you will see it marries up with the same design of the plug, are you sure the plug on the new cable you have purchase is exactly the same as the one you are replacing?   

[#12]

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@2u2me wrote:

Hi there, I don't think its the new cable that is at fault its the actual plug on it, RJ11 plugs and sockets are specific to each other so you need a new cable with the exact plug on it as the one you are replacing...

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Thanks for that. I haven't closely compared the new cable's plug to the existing ones; I'll do so in the morning. But I'm rather surprised by what you say: if RJ11 plugs and sockets have to be specifically matched to each other in order to work, doesn't that make nonsense of the standard?

[#13]

No, what I am saying is you can insert a RJ11 plug into a RJ45 socket and vice versa, but the connections will not marry up

you need something like this.

RJ11 to RJ11 ADSL Cable for BT Broadband Router | DSL Modem Internet Lead UK – Esellertree

[#14]

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@2u2me wrote:

No, what I am saying is you can insert a RJ11 plug into a RJ45 socket and vice versa, but the connections will not marry up.

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That wasn't what you said. But in any case - as I thought I'd made clear - I'm not trying to insert an RJ11 plug into an RJ45 socket, much less vice versa. Why on Earth would I? I might not be as technically clued up as a lot of people, but I certainly know better than to try that.

My point was that the R11 plugs on the new cable are significantly smaller than the R11 sockets into which I'm plugging them, which could perhaps be causing poor or non existent contact.

[#15]

Sorry, just to clarify: my point was that the bodies of the R11 plugs on the new cable are significantly smaller than the R11 sockets into which I'm plugging them, which could perhaps be causing poor or non existent contact.

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