thanks for the replies guys. i will do some more proper testing as you metionned but playing around some more, here is what I found:
And the real kicker is that it seems to do this (probably to a lesser extent) even when pluged directly into the modem, no router involved!
I can test a few times in a row and get 21MB/s but then after a while I will get 18 then 14, 11, all the way to 3 (!?). It will pick up again but takes a while.
I really need to contact my ISP.
What is even weirder is that once I do get a test that says I'm getting 3 MB/s, if I try right away to download a large file, let's say an Nvidia driver (170 Mb or so), I get blazing speeds of over 2 Mb/s. It really seems like the speed depends on what you are asking of the connection. Torrents, although unstable, tend to be very fast most any time.
I do have VoIP instead of regular phone so I have no idea if this affects anything. But without the router, VoIP is out of the equation, at least I think...