they should be all compatible with each other, so you may try different wall sockets, and try to exchange the v2 and v3's location to have a test(make sure the house light on v3 are on as well which...

it is not recommended, some power extension board has filtering function which will block the communication between the two units

It can be plugged into wall socket directly

Before you install that driver, you may go to device manager and check the device status of that adapter, if it shows the device is working properly which means the driver has already been installed,...

are you sure the WN8200ND was able to recongnize 5G SSID? I checked the specification on tp-link website, it seems that it only supports 2.4G SSID

what is the hardware version and firmware version of your range extenders? any it is EU or US versions?