Ongoing connection problems.

I've been having issues with my internet for 2 months now. 

My downstream connection seems to fluctuate. 

Cox came and look at the issue several times. They have replaced the whole line inside my house, the modem, connections outside. They have checked my neighbors modem, and nobody seems to have my problem.

Sometimes it seems when I place the modem a certain way, the fluctuation seems to stop. I move it 1/4 of an inch and problem starts again. Then I have to play with it for hours until I find a position where it doesn't fluctuate as much and I can use my internet. And even then it starts fluctuating eventually.

Was wondering if anyone had the same issues or if anyone has any suggestions