Xb7 wifi rf power issues

This unit replaced an xb6 unit that worked for several years feeding two wifi repeaters years before even the first generation of the xfi pods.

I had done an extensive wifi RF review before installing those repeaters, and they ran perfectly for years.  But the new xb7 wifi signal levels are significantly below that of the previous unit, even to the extent where the polar levels show a drop of over 15db from one radial to another at a distance of only 20ft.  

Is this new unit defective, is the testing of the mimo design wrong, or?  This is the arris unit.  

I'm currently trying to move my repeaters to bring their operation back up to what it was with the xb6, but having to move them to within 20 feet of the gateway is rediculous to get good operation is bad, where before 40 feet was providing excellent throughput.