On WD MyCloud EX2 you can assign an ipv6 address, but it can’t be used for anything. Sure, you can ping it, but that’s all.
Ipv6 file sharing (file sharing is the main reason to have a nas)
WS Discovery (so it shows up in ‘Network’ folder on Windows and can be browsed)
Ipv6 is not a fashion thing, that goes away again, it’s the future of internet and WD should implement it properly in it’s products.