How many satellites for WiFi 7 in tall old home?

redheadkxc wrote:

I have an Orbi RBR50 with three satellites in my 3-story, 125-year-old home with lathe plaster walls. The RBR50 is on the 2nd floor, satellites on the 1st and 3rd floors and an outdoor unit in the garage for summertime patio use. Now that the RBR50 system is no longer supported, I'm looking at WiFi 7 systems and wondering if I still need as many units to overcome the old walls. 

FWIW, the regulatory wifi power limits haven't changed much since the RBR50 was released.  I used to use an RBK50, but am currently using an Orbi 870 system. 

The backhaul in the 870 (and almost all wifi 7 mesh systems) is different - it uses the same radios as the client network.  The backhaul has better performance because it can use multiple bands (generally 5gz+6ghz).  But not really more range, as that is limited by the power limits.  I do recommend getting a system with 6 ghz, even if you don't need 6 ghz for your current clients.  The improvement in backhaul performance over 2-band mesh systems is significant.

I have a similar home - 3 story, lathe plaster, ~120 years old. Somewhat smaller than yours with only one central chimney.   No outdoor AP.   I am using two 870 satellites with no coverage issues.    The router is currently in my basement (co-located with the ONT) - both RBS are on the second floor.  I am using a wired backhaul to connect the satellites to the router.  That's a new placement (a couple weeks).  Before then I had the router on the first floor (satellites in the same location), and used the wireless backhaul.

So you might be able to get by with two satellites - one avenue is to try a couple of alternative placements with the RBK50 setup, and see how well it works.  

The original walls are horse-hair plaster on a wooden lathe (some have been replaced over the years with modern plaster).  They don't affect the wifi much - a metal mesh lathe or concrete with rebar would be a much bigger challenge.  The issues for me are the central chimney and a pipe chase - both do block the signal.  I needed to work around them when using the wireless backhaul, which constrained my placement options.