Everything from AV200 to AV2000 is compatible.

Yessir, I have two PA4020s and one PA4010 connected. hope this helps.

I have had several av1200 and below happily talking to one another for some time. I just got two AV1000s and they most definitely do NOT talk to these. All are tp-link. I get red lights on the av1000s even when adjacent to the av1200s.So no, they are not all compatible.

From a standards perspective, they should be. Did you follow procedure to add the new adapters into the existing network?

Peter M wrote

From a standards perspective, they should be. Did you follow procedure to add the new adapters into the existing network?

Absolutely. They join the network, but with hardly any connectivity. I have tried both plug and play and also by encrypted join, the latter I even tried with just one av1200. In that case, both red lights came on. There is no way these can be mixed.

I gather tp-link have gone through several versions of av1200, thee are v1. Did they abandon this version in updates? I don't see any newer firmware than what I have. Mine are compatible with av500 but not av1000. I have not tried av500 to av1200 compatibility but will report back.