BTW - the new firmware update has NOT resolved all the issues. Tests done today:
Firmware: 3.0.0.4.378_6759-g029d0d1
2 x RPTs - works
2 x AP - does not work
I'd just like to echo all the comments above about how disappointing it is that some of these devices are this bad. Fortunately I have installed other RP-AC56's & they are working fine, not perfect but fine, so I know that they can be a good product. Unfortunately I spent hours yesterday trying...