Random Question, but what is the speed of the Fibre cable that enters the FTTC DSALM? The Infill cabinet that we have is fed through standard Fibre Nodes strung along poles, just like a FTTP install all the way back to the Agg Node, but what speed would the cab recieve before it gets capped at 80/20 to customers?
Would be interested to know! Ive been on BT FTTC since 2013 according to my Speedtest.net records. My speed averaged between 50 - 53mbps DL speed with the highest being 56. In the last 18 months Ive been experiencing unprecedented dropped internet connections (not wifi), lasting less than 30 days at a time.
I complained to BT about my now regular disconnects and all they have done is slowed my speed (to 47mbps). Sometimes when I do a speed test, Im down to 37mbps!
Your problem is not related to the speed of the fibre backhaul from the cabinet.
Dropped connections are due to problems between the cabinet and your house, and capping the speed at which the VDSL modems train up does indeed improve the stability (at the cost of speed, of course).
The most likely causes for the loss of stability you've seen over time are:
1. degradation of the copper/aluminium network between the cabinet and you (e.g. water ingress)
2. crosstalk due to increasing numbers of customers taking up FTTC instead of ADSL