mine is fairly new I built it about 7 months ago
here is tonight test
OK, so not your LAN then - and sometimes you get full speed.
I suppose you could be getting intermittent noise = some loss on the wan - maybe if you have a Hawaeii you could unlock it and see.
Assuming you are synced at 10 up 6.1 seems low - but then I've read that Hawaeii have QOS enabled which hurts upload speed but can be turned off if you unlock it.
Maybe someone else could say if 6.1 is normal up speed for 10 sync.