Noob struggling w/ very slow speed

Hi all,

I am having a problem with my Synology USB Station 2 that is making me tear my hair out, and I really hope that someone can help me.

I have a USB Station 2, and I recently got an Asus RT-N56U router. My problem is that when I connect the USB station to the router with a Cat6 cable, I get very low speeds - around 100 KB/s!

I have tried testing the cable directly between other computers, and it works fine, I have also tried two other Cat6 cables with the same result. Also, my attached HDDs are formatted as EXT4, which should give the best transfer speeds.

The weird thing is, that when I connect the USB Station with an old cable I have lying around (I think it is Cat5, but I'm not sure), I get decent speeds of around 10-12 MB/s, which is still not good, but better than the slow speed I get with the first cable.

I assume that it is the router settings or network settings on the USB Station that is causing it, but I really can't figure out what to do. I hope that someone can help me out!

Thanks!
/Rasmus