I have done more tests between my new PA9020P and the old PA8010P. Connection between both models is very unstable, pings gives times between 4ms and 1000ms. I have tested with another AV500 from Netgear and connection is more stable. So conclusions:
- Mixing pa8010 and pa9020 isn't working fine. very unstable network speeds, pings and packets lost.
- pa8010p and pa9020p gives me the same speeds
- mixing pa8010 or pa9020p with netgear av500 seems much more stable and fast than mixin pa8010/pa9020 on the same network

Please helps TP-Link support team, if we don't find a solution I'm going to return PA9020 to amazon.

I have had similar issues with the 9020 for months. TP-Link don't bother replying despite this being advertised as a vendor technical support forum...