Lockable?

"Unfortunately, it's open to anyone on the same wifi signal as the Sonos system." - Meaning NO
"If you restrict those who get access to the system, that would take care of it." - Meaning YES

Which one is it?

"Unfortunately, it's open to anyone on the same wifi signal as the Sonos system." - Meaning NO
"If you restrict those who get access to the system, that would take care of it." - Meaning YES

Which one is it?

It's both. Anyone with access to your WiFi will have access to Sonos. If you restrict access to your LAN WiFi, by using the "Guest" account setting on most routers, then you can give your guests the "Guest" SSID and password and they will only have access to the internet, and cannot access Sonos (and other more important things on your local LAN).

Absolute rubbish this is. I have 2 play one’s and 2 play 5’s. I live with my family. The problem is that my kids can control my system by just downloading the app and connecting to the WiFi network. What Sonos are expecting customers to do is set up a special network for just the speakers and inciting extra cost. No I am not going to make a guest network for the family or anyone else. It is the same with customers who live in shared homes. This is their system and not for anybody else. Sonos staff please sort this. There needs to be an admin function on the app. I am seriously considering returning my products under the sales of goods act and purchasing a competitive system.

With the vast majority of modern routers, there is no extra cost. Most have a guest account built-in.

As to you threat, the sales of goods act won't protect you, for Sonos has never claimed to have this functionality. As to a competitive system, perhaps you could list the ones you are considering that have this feature, some reading this thread might be interested.

It will. Within 30days of purchase. And I will also put it out there on social media seen as Sonos don’t mention it.
As for competition always liked B&O

Also to add. If you live in a shared house, you are not on the admin profile for that network.

It will. Within 30days of purchase, And I will also put it out there on social media seen as Sonos don’t mention it.
As for competition always liked B&O

Funny. We in the US get 30 day returns for any reason. Nothing to do with sales of goods laws or warranties.

I've never heard that BeoPlay speakers have this function, can you confirm? If so, I guess if you have the cash for art over electronics, they are an option.