Having been struggling with the issue of HomePod minis repeatedly losing connection, and the two software updates not fixing it, I think I may have discovered the cause, at least in my situation.
The issues I’d been seeing were with my Minis in my living room, which are a stereo pair and are the farthest away from an access point (I have multiple APs throughout the house), is they would regularly lose the internet connection. This would cause issues ranging from the stereo pairing breaking, to Siri saying she was having trouble with the connection, and it would cause issues with my HomeKit setup and give me disconnected notifications for my HKSV cameras, when one of the Minis had been acting as the HomeHub.
I have a 2.4GHz / 5GHz network using the same SSID (WifI name) on both networks so devices can seamlessly pick the better band without having to provide multiple connection passwords.
What appeared to be happening is my Minis were flip flopping between the 2.4GHz and 5GHz bands, losing connection each time before eventually reconnecting. No other devices in my house appeared to be having this issue, as modern WiFi devices are designed to cope with this setup.
However, what appears to have been causing the disconnection issues was a feature called “band steering”, referred to as “Smart Connect” on my Netgear APs. This is a feature where the AP will try to push the device onto the “better” WiFi band to improve the connection. However, in the case of the Minis in my living room, they weren’t dealing with the band steering tidily (for whatever reason) and this was causing them to lose the connection.
Having disabled band steering (Smart Connect in my settings) things have settled right down. I’ll admit it has only been around 35 hours since I made this change, however we have not encountered connection issues with the Minis and I’ve stopped receiving HKSV camera disconnected notifications, where I had been receiving around 10 to 15 per day, previously.
Your mileage may vary, but if you’re having connection issues with your HomePods and your router has a band steering feature, I would try disabling this to see if it helps.