Disconecting Router, ISP or both???
You tell us......What is the DSL uptime and ISP uptime recorded by your router?
Does your noise margin wander from 14dB (looks like you've already been placed on a 15dB target, due to connection issues)?
BT Wholesale says I should be able to get 1.5mb downloads
Then, as you have a connection speed of 1856kbps, they're not too far off.
currently connected via a wireless adaptor
I assume you've checked the obvious (that it still does it when you connect your PC to the router, using a CAT5 Ethernet cable)?
Ade
ADSL24/Entanet - 16 months and counting, with Entanet!
DL Sync 4000kbps
UL Sync 448