The #1 thing you should know before you buy Sonos or expand your existing Sonos system

I spent the last few days debugging a problem which should not really happen, but it did. It made no sense, and in finding the solution I learnt quite a bit of things about how Sonos works with WiFi. I think everyone who buys a Sonos speaker or who is adding more Sonos speakers should read this article because what I found out blows my mind!