Hardware Version: V4

Firmware Version: 3.2.4_902104_190506_901

I get slow internet throughput on my PA9020P. The line rates are high - which I can see from the TPLink utility for PA9020P 700-800Mbps; But the internet throughput never exceeds 180-190mbps; it is maxed out at this speed; I have a 1000Mbps rate internet connection - I get the full speed throughput (ookla speedtest) at the router; but when the client devices access the internet via the PA9020P remote end it is limited to ~170mbps, close or far, at any line rate. 

I have seen several complaints posted about PA9020P with this problem and already tried a troubleshoot path 'case 1' and 'case 2' from TP-Link. I've also tried disabling Power Saving Mode which had no change in internet speed, and enabling Lower PLC-to-VDSL Interface mode which reduced my internet speed even further. 

Also tried playing with QoS setting on PA9020P but that does not help.

Any suggestions?