If you’ve updated your Apple devices to 16.3 and finding that you’re having connection issues, here are some of the things you can try. I’ve heard reports that people are having issues especially with the HomePod not connecting when running on 16.3.
Restart your Wifi Router
The easiest thing to try is simply rebooting your Wifi router. Most HomeKit connection issues are usually related to the router.
Reboot your HomePod
If you’ve got HomePod, try a hard reboot by unplugging and then plugging it back in again. I’ve found that this usually fixes connection issues related to the HomePod.
Check your Network Settings
I’ve found I can fix most issues with HomeKit connections by making sure the network settings are correct. Firstly, make sure you’re using 1 SSID for your Wifi Network. Many people use different names for the 2.4ghz and 5ghz networks. This can cause issues with some smart devices thinking they are not on the same network as your HomePod/Siri.
If you’ve played around with settings on your router, you may have inadvertently made things worse. I’ve often just done a factory reset of the router and it fixes things.
Reset your HomePod
This is definitely annoying to do, but you may need to reset the HomePod. This can be done through the Home app on your iPhone. This tends to be a last resort step but it usually fixes most issues.