iOS 16.4 Home HomePod HomeKit wifi network always changes

You're right to be looking at the network... For all iOS devices, have you turned off the 'Private Wi-Fi Address' feature? I don't believe the HomePod or Apple TV use the it, but they depend on peer-to-peer comms with iOS devices and other devices (bridges, routers, mesh wifi access points, etc.) can get confused at changing MAC addresses. I think the feature is a solution in search of a problem and should certainly be turned off for your private networks.

Use private Wi-Fi addresses on iPhone, iPad, iPod touch, and Apple Watch - Apple Support

If your iPhone is the device that set up HomePods, it’s going to use the network the iPhone is on. It’s designed to work that way. You can try installing the most recent update to 16.4.1 to see if this has changed anything. Otherwise submit feedback suggestion that you’d like the option to have more control on which network you use: Feedback - HomePod - Apple

I was addressing the original poster with multiple networks. Some routers have both a primary and a guest network, in which case you'd only want to connect your own devices to the primary network. As bgmeek points out you don't want to Use private Wi-Fi addresses on iPhone, iPad, iPod touch, and Apple Watch - Apple Support on your own network as this can prevent devices on your network from being able to talk directly to each other.

tt2

Mine too. My light switch and TVs rarely work properly. I have to turn Wi-Fi on and off or try airplane mode to get it to connect. So annoying. HomeKit doesn’t work right 90% of the time. Alexa does tho-

And how do I “forget any networks”? I have one network. My home Wi-Fi, correct? I’m not connected to my neighbors Wi-Fi. So, please speak in layman’s terms. What should I tell my phone to forget??

Your Wi-Fi connection settings are going to sync from your iPhone to your HomeKit devices. You should forget any networks that you don't want the HomePod to connect to.

tt2

Thank you. I have turned it off.

should I turn that off on my Mac computer as well. It has trouble connecting to my printer all the time as well.

thank you again

Yes. In general you don't want to use private Wi-Fi addresses for your own devices on your own networks as that can stop them from being able to communicate with each other.

tt2