I have a Draytek 2820.

Syncs at between 2 and 3 MB downstream

I tried a Belkin router and a Netgear - they all sync at 5 - 6 .

Any idea why?

I am on a BT exchange - 21CN - ASDL packakadge as the line cannot take ASDL 2+ due to the length of my phone line!

Is it a firmware issue? Do I need to try an alternative modem firmware?

Try the 211801 modem code, that is a pretty bad difference though, I haven't seen that sort of thing with my 2820, more like half a meg less than ISP supplied hardware.

I do not understand this but..

tried all firmware updates etc.

No difference.

Decided to reboot using factory defaults - and - having reconfigured with IDENTICAL settings - it goes back to speed!