Is There An Upload Throttle?

Home Internet Throttling

Is there an automatic throttle on Home Internet upload speeds?

I've been trying to upload a large set of filea via rsync (so, not torrents) to a single-point receiver out on the net. Think about a large video upload to YouTube or to my own website, that kind of thing.

I've seen upload speeds of as much as 9MB/sec, but on more than one occasion, including a few minutes ago, somebody dropped the hammer and it's gone down to about 130k/sec. It can stay there for days, or not, before it magically goes up again.

Download speed isn't affected, and it isn't network congestion because it's 3 in the morning.

What gives? Is there a ban hammer limit? If so, where is it set? This wasn't disclosed beyond the usual network congestion disclaimer.

ETA: I am using my own router plugged into the trash can running a recent version of DD-WRT and have no other trouble with it.