The add on disk for Whole Home Wi-FI rear packing says "Connect up to 6 discs round your home*).
Great except that little star means September 2017!
So whilst I think I have 6 discs connected in the network I can only see 4 in the app so cannot be 100% plus managing is a pain.
I'd hoped for better from BT. The 2 sets of 3 may be going back.