So bit of an issue here short of sending someone to your house with one of our laptops I'm not finding anything. Actually I told your "modem" to do some FTP tests and it maxed out every time.
Today I see that you've had a 10mbps download running since about midnight I figured Hey let me stack my test ontop of yours.
And Two more samples, first one is since the other day you can see the "spikes" where I had your modem download a 2gig file.
The second is when I just stacked it ontop of your existing transfer this morning.
So yea, ontop of the results that I got back from someone testing off your grouping I'm kinda stuck. I can see about sending someone out there next week with one of our laptops to see what happens. maybe they do better maybe they don't?--