Should be compatible: I plug in the PL1000 adapter and the PLW500 access point next to each other and press the security buttons on both for a few seconds. The PLW1000 identifies itself as NETGEAR21_EXT, the old PLW500 as NETGEAR_EXT. I have the impression that the old PLW500 transmits much weaker than the PLW1000, OOKLA measurements are still pending.
But the main problem is: With the software "Netgear Genie" it has been impossible for me to make security settings on the adapter. With every recommended password, an error message came up. It may be my fault, but the instructions, including those on the website, are imprecise and do not include screenshots of the Genie software. So far Netgear has not responded to my question, I will write again and hope for an answer. Maybe you can give me a tip.