After a week of debugging everything I could think of & also trying a whole variety of setups - I finally have some Progress!
It seems Asus tends to automatically enable 'Protected Management Frames' whilst using WPA2/WPA3
WPA 2 Personal allows the PMF to be disabled & it 'MAY' have fixed it (still early but promising)
401's don't like PMF 🤣
#Bitaxe