Hi community, 

I am looking for recommendations on what's the absolute best deco in terms of range, I am confused there are so many models. 
 

I bought a 3 pack of M5s last year, but they didn't cover the whole house. So I added another 3 pack and still there are dead zones. I read 6 units is the limit for M5s, so I guess I can't add more now...? 
 

Can someone tell me which ones I should get, which are the absolute best ones?

the house is 2 floors, quite large (around 6000sqf) and all walls are concrete. And I also need one or two outdoor units to cover the garden (for cctv and ring door bell). 

If anyone are experts here, what do you recommend? 
 

thanks