I have ADSL2+ (BT 21CN) and am close to the exchange Line Atten 20/12 S/N 6/6.
When I connect either my Fritz!box 7390 or 7270 or Technicolor TG582N The Sync is 16.5/1.050. However if I connect either Thomson ST780 or ST585 v6 the line syncs at only 2 - 2.5 mbps download and correspondingly low upload speed. The Thomson routers show ADSL G992.5 which I believe is ADSL2+ they also have the latest UK firmware 184.108.40.206.
I found that if I use the CLI Command to force the ST780 into ADSL2 mode instead of ADSL2+ it syncs at 10.5.
Question is does anyone know why these routers don't work properly in ADSL2+ mode.
Incidentally I tested the same ST780 on my line back in December and it synced at 16.5mbps. Same story at my neighbours with the same router - used to sync at 16.5mbps now 2-3mbps unless forced into ADS2 mode.