This may sound drastic but you might need to drop your downld speed as well.

Can you give us more details about your actual connection devices. It sounds like something a usb modem might do, but you said ethernet in your 1st post. And what do you mean by 10/100? What is the actual speed of your service? Also you can check the speed here: http://www.t1shopper.com/tools/speedtest/ (choose your country) or here http://www.adslguide.org.uk/tools/speedtest.asp & another with other tests is here: http://www.broadbandreports.com/stest