I'm experiencing similar issues with my PA7017 kit. I have a 1000Mbps internet connection. I have tested (with my laptop's ethernet connection) a direct connection to the modem to give ~850Mbps (with speedtest.net). Then I added the 2 powerline adapters in the middle. Now I'm consistently getting ~150Mbps. I've tried moving them to different sockets, same results. The tp-link tool shows ~600Mbps connection between the powerline adapters, but I'm not getting anywhere near that:

Clarifying again, there's no other adapter on the way to the modem, and direct connection to modem gives ~800Mbps, so the bottleneck has to be the powerline adapters
I've updated firmware, got the same result:

How can it be that those adapters show 600Mbps between them, but internet connection is 150Mbps? that's x4 slowdown. I just paid extra to replace my older 100Mbps to those 1000Mbps adapters, apparently with no good reason to do so...
@TP-Link