What was your original estimated speed?
As take-up increases in the cabinet, crosstalk from other customers will reduce your speed, and/or increase errors which are likely require the addition of interleaving and FEC - so reducing speed further.
BT's original speed estimates were pessimistic because they already accounted for this effect. But take-up rates mean we're still in the process of seeing the effect in practice.
How much speed can be lost? The overheads of FEC, when turned on, can instantly take away between 10% and 25% of your speed. On top of that, more speed can be lost by the increase in interference/noise that doesn't cause errors. Perhaps 40% overall - but every line suffers differently.
Your drop of 65-50 is very close to 20%, so it is highly likely that the majority comes from just having interleaving and FEC turned on. If you are around your estimated speed, then this is even more likely to be the case.
The solution is vectoring, which should take away all the crosstalk, and restore service back to close to pristine. In the
reports describing how good vectoring is proving to be, the graphs that show the improvement also imply (in reverse) just how much speed can be lost as your neighbours add to the take-up on the cabinet.
Plusnet Customer
Using FTTC since 2011. Currently on 80/20 Unlimited Fibre Extra.
