2 floor house + Outside is immediately 3 APs. You'll also need at least one PoE switch to power them. That's 4 devices already, without adding anything else like security cameras or similar.
isn’t that typically the implicit message being sent by disgruntled customers complaining about a company’s seeming lack of foresight or excess of greed, or both?
Unless all the walls in your house are heavily reinforced concrete, I don't see how you need that many APs.
This kind of setup is easily achievable with UniFI POE gear, but will hit the 5 device limit of this router. The original USG didn’t have this limit.
Having one AP per floor is normal for coverage, so that would be 4 to serve the inside.
And even in a brick house a lot of the interior walls are still just plywood or drywall, even in the UK AFAIK.
What is interesting though is that OP said it is sufficient with one AP per floor plus one outside. So apparently propagation within one floor is fine, but between floors or to the exterior is not. In that case, it has to be a building where the interior walls are mostly just drywall, and the exterior walls and floor slabs are reinforced concrete with little in terms of openings. Which sounds more like an apartment building than anything else?
[1] https://www.nist.gov/publications/electromagnetic-signal-att...
We’ve got 3 UniFi APs downstairs here, 2 up. There are still things on the periphery that only just cling on, and when you’ve got stuff like that it takes a lot of airtime.