unstable connection?

[#1]

At the weekend i noticed a speed drop on my line. Went from 6.5mb to 3mb. The router downstream had gone down so i did the reset. speed went up to 5.5mb there it as stayed. I did contact via email but didn't really get anywhere. Since the weekend Xbox games have been a bit laggy. Today the speed has been erratic and keep being signed out of Xbox live. Have checked with friends and the Xbox live status they are fine.
**edit**  just checked live status again they saying there is a problem. But doesn't explain what been happening since weekend.

[#2]

Hi there,
I've posted a graph of your connection below, the majority of these appear to have been done by you?
<img src="http://ccgi.psmith12.plus.com/visradius/generated/image13606604138870.png"/>
Attached is also a graph of your sync speed over the last 14 days which has only had one very little change. Are you connecting wired or wireless?