DG834G download rate problem

I have a Netgear DG834G. It has performed flawlessly until last week when
my my download rate (monitored using a speed test web page and netmeter)
was approximately halved from 450kbps to 200kbps. This is using a cable
between PC and DG834G. Changing the firmware, factory reset does not
help.

If I use another ADSL modem the download speed is fine and normal.

The bandwidth is there on the DG834G as well but only if I set 3-4
downloads going at the same time which isn't much use to me.

I assume the router is broken?

Regards
Jeremy Robinson
Limerick, Ireland