I've been fighting with this router for 2 months now, even to the point that an RMA was issued and a replacement sent.  My original problem was the QoS cutting my speed in half, after getting the new router it was fine.  But suddenly it's decided that 1000Mbps is to fast so it changed the port to 100Mbps.  

I've gone into Advanced-system tools-system parameters to edited the duplex, changed it to 1000Mbps full-duplex.  It changes it back to 100Mbps . . . Oh, it must be a cable problem - it's not as stated above I was getting over 400Mbps prior.  

What can I do other than throw it out the window?