That proves then that the problem is with the white cable connected to the A&B terminals is the source of the problem. Either there is something connected to it that isn't filtered (that you are not aware of) don't forget things like alarm systems, ringers or sky boxes that may be connected to the line, or the cable is picking up interference and needs to be replaced.
no matter which cable is using A and B, the speed drops to 8-9mb both at master and at extension with filter.
If I unplug A and B and only use 2,3 and 5 at master, i get 15mb.
The filtered connection is working, but the unfiltered connections are being restricted at the master. should I ask for a replacement XTE-2005?