RJ11 cable issue

I am with EE and have a Brightbox 2 router. I get around 59mbps download (9.2 up) speed using the 2 metre RJ11 cable that came in the box. The Openreach socket is a new-ish Master 5C with 2 outlets. No phone line plugged in, we don't use the landline.

I want to move the router and bought a 5 metre RJ11 cable. To my dismay, changing the cable resulted in a 12mbps drop in speed ! I changed the cables a few times, in case I had a bad link, same result. I bought another new cable, in case the first one was faulty. Nope, same result.

I then found a 5 metre cable made with CAT5e so bought that, the drop was only 10mbps, but still very significant. All told I now have four 5 metre cables, from different sources (to rule out a bad batch) and get the same problem if I swap in a 5 metre one.

I brought this up on the EE community forum and have also contacted EE tech support. Nobody seems to know why changing the cable for the same spec or even better spec would cause such a drop in speed.

EE have done remote tests on the router, all is OK as far as they can tell. They have no idea why I should see such a drop in speed and have nothing on their system from other customers like this. The line itself was re-provisioned in July 2017 and fully checked by Openreach at the time.

I've a few ideas to try. One is to swap out the router and try another, I have one on it's way. Another is to make an extension to the Openreach socket and put a broadband splitter on so the change in distance is via phone line, not the RJ11 wire.

But, it still sounds odd that a short distance change in a bit of cable can cause such issues... Just to test the theory that it is significant I'm going to try a short run of cable too, see if that bumps the speed up at all

Has anyone ever seen anything like this though ?

When you change the 2-metre for a 5-metre, are you checking with the router in the original location, or at the desired new location?

I assume you are doing it at the current one, but I'm just making sure. In case something at the desired location is causing the problem.

Edit: Also are you talking about the sync speed, or speed test results?

Edited by RobertoS (Wed 09-Jan-19 15:30:32)

Good point, but at the same location, no move made apart from change of cable. Knowing that I'll need to swap it back...

Speed test results and sync speed - both are affected by changing the cable.

Sync speed changed from
Upstream 9928 (Kbps)
Downstream 59460 (Kbps)
to
Upstream 9865 (Kbps)
Downstream 48292 (Kbps)

Speedtest from
59.30 Mbps 58.55 Mbps 9.03 Mbps
to
42.94 Mbps 30.17 Mbps 7.59 Mbps

giving typical examples from my profile results.

Hi TMCR

Just a pure guess.

could all the 5m replacement RJ11 cables you bought be using either CCA (copper clad aluminium) or CCS (copper clad steel) rather than just copper as that could affect the speed over a short distance.

Or are constructed so that the twisted pair is not used.

A 5 or 10m cable SHOULD NOT introduce anything like this sort of speed drop

I've used a >20m cat5e cable to connect my router to the master socket, and there is absolutely no change in stats.

I use a 5m RJ11 cable and have no issues with speed drop compared to the standard 2m flat cable. I purchased the "kenable ADSL 2+ High Speed Broadband Modem Cable RJ11 to RJ11 5m WHITE" from Amazon for a couple of quid.

It could be a fault with NTE5c in that the inbuilt VDSL/ADSL filter is faulty.
It could be causing a dip in the HF response of the overall line combined with the extra 3m of cable on the rj11 lead. Just a wild guess, but it may be worth replacing the NTE with a new one.

Copper clad is a possibility, but no way of knowing without stripping the cable back.

One of the extensions uses CAT5e cable... ?