The main telephone socket is giving me less internet speeds than the extension outlets. 30% less. Upload speed not affected.

This is after replacing with new socket/new outlet, I never used the old one at this location.

The difference in wiring between extension and main, is main has more wires crammed into one telephone socket. All I did when installing socket is join up similar colored wires into one hole. There were 4 cables, each had 2 wires in them, blue and white. The new socket design has 4 pairs of holes, designated as 1, 2,3,4. Pic of design:

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Each designated pair of holes, I put two wires of similar color from two cables coming from different directions.

The extensions have only one cable with 2 wires, blue and white.

What did I do wrong?

  • Hire a professional?
    – Kinnectus
    Aug 16, 2016 at 10:23
  • As a last resort, but might as well finish it if I can.
    – Altoban
    Aug 16, 2016 at 10:27
  • If the wires are twisted pairs and they were unwound two far this can affect the link. It is possible your provider limits your download speed since upload speed is not affected.
    – Ed Beal
    Aug 16, 2016 at 13:17
  • Check the connections and see if they're loose. Alternatively you might be seeing interference from elsewhere. Try temporarily pulling the downstream wires out of the connection so its just the main going in.
    – Steve
    Aug 16, 2016 at 13:22
  • If you remove the extensions from the main (so the main only has the incoming wires connected to it), does anything improve?
    – brhans
    Aug 16, 2016 at 13:52

1 Answer 1


So this ADSL/VDSL ?

The outlet you're using is an RJ11 ?

By the sounds of it you have too many wires coming for most mechs, Krone can take up to 4 due to double punching and 2 terminals but most can't.

Test your speed at the ISP demarcation point. Just because the 'main' socket has the most cables going to it doesn't actually mean it is the closest socket to your lead in cable. It is quite possible one of these other 'extension' sockets is actually the first outlet and you potentially have cable issues from to the 'main'.

  • Am I supposed to put all wires I have to one socket? I don't know if some of these wire belong to extensions rather than coming from outside. If that's the case then they just there to share connection. I was thinking of separation, where only two wires for one socket for ADSL, and other for phone. But that night not work as phone might need all these wires connected.
    – Altoban
    Aug 17, 2016 at 2:20
  • It depends entirely on your phone system. Unless you have a 2nd phone line, it will be on one pair only. From the sound of it you have star wiring from this 'main' socket. Do you have a photo of the actual socket and wiring and do you have some idea of the topology? Ideally if you can connect a socket directly to your lead in cable and test that it should rule in or out issues with your other sockets and wiring.
    – D-on
    Aug 17, 2016 at 5:42

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