I know why it is now!!!!!
The unplugged,plugged,unplugged................
It a Temprature issue,...
I dont know if anyone has/had this problem before or if anyone posted this, but if the xbox is too hot it will turn the LAN on,off,on,off....
I noticed this because I was getting great speed lately, but just now I was playing a game for a few hours and it was running pretty hot, then I tryed tranferring over some files and it started again...then I thought the temp cause what else was diferent from before i played the game.... so I increased the fan speed, pulled it out of my tv stand and tryed again....
And no-more on,off,on,off........ i'm back to 7-8MB/s on avrage, I get burst of up to 33MB/s but thats not really acurate
dont think it would even be possible on a 100Mbit line.....
Anyhow I hope this helps to anyone that has this issue.... let me know if it worked for you as well