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    Sky MAX slow connection, ADSL2+ in Exchange - faulty DSLAM?

    This is a discussion on Sky MAX slow connection, ADSL2+ in Exchange - faulty DSLAM? within the Sky Broadband help forums, part of the Sky Broadband help and support category; Hi SkyUser guys and gals, First time post and all that... your help would be very much appreciated. I was ...

    1. #1
      ahirshfield's Avatar
      ahirshfield is offline Sky User Member
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      Sky MAX slow connection, ADSL2+ in Exchange - faulty DSLAM?

      Hi SkyUser guys and gals,
      First time post and all that... your help would be very much appreciated.

      I was connected to Sky Broadband MAX about 2 months ago and have experienced quite a few issues.
      As a Telecoms engineer myself (T-Mobile) I have diagnosed and corrected most of the usual problems myself:

      • Wireless drop-out – change security settings to WEP and disable UPnP (precautionary).
      • DSL losing sync – reduce noise; test using BT master NTE5; remove ringer from extensions.
      • "LCP is down" error – establish higher signal to noise ratio with above fixes.

      The single remaining problem is a severely reduced downstream bandwidth/speed of between 3-4 Mbit/s.
      I am certain that the local exchange "Welwyn Garden City" is ADSL2+ enabled as Sky have installed their own DSLAM for LLU.

      All CRC, ES and other error stats on the detailed modem stats are fine, while the Max(Kbps) down is currently 4216 with Rate slightly lower.

      My distance to the exchange is 1.5km and BT have checked the line as 100% okay on all remote tests between the exchange and my premises on a brand new build development.
      With all usual variables considered I should be technically and physically able to achieve between 8-16 Mb, or at lease significantly higher than I currently connect.

      BT assure me of no line issues (and I concur) and Sky CS are as usual incapable of deviating from their script suggesting a wireless issue or problem with my computers - regardless of the fact that I inform them the connection is established and reported between the router and exchange!

      Anyway, waffle aside, as a trial to diagnose the slow connection I tried the following:

      • If I use Mognut’s Utility to change from G.DMT Mode to ADSL2+, then the router is no longer able to connect to the exchange given any amount of time. It just remains at a "Negotiating" or "Disconnected" status.
      • Reverting back to G.DMT Mode allows the router to reconnect at the previously low speed.

      Does this signify a potential issue, configuration or otherwise, with the sky DSLAM at my exchange? Does anyone else experience any of the above and how would one go about resolving such an issue?

      Thanks for all your time and assistance,

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    3. #2
      Saturday's Avatar
      Saturday is offline Sky User Super Mod
      Broadband ISP: Sky Broadband Unlimited Pro
      Router: Sky Hub SR102
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      Re: Sky MAX slow connection, ADSL2+ in Exchange - faulty DSLAM?

      Sky will generally only put connections on ADSL2+ if the line is capable of supporting >8000kbps i.e. the line is relatively noise free and the attenuation is<~42db (you didn't say what your attenuation is). In all other cases the connection will be put on G.DMT and it is not possible for the customer to change to another mode.

      It is entirely normal for the max rate shown to be slightly higher than the actual sync rate. If your router is syncing at ~4000kbps then it means that this is the highest speed your router can sync at i.e. your attenuation is ~55db or, if lower than this, then you have line noise which is limiting your connection speed.

      If you haven't already seen/read it then you may find the first sticky in my signature at the bottom of this post a useful guide to the relationship between attenuation, noise margin and sync speeds.



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