Hello Andy.
i am in the same boat as you.
The HomePod I have is close to becoming the HomeLandfill.
i have an iPhone15 Max Pro, and a TP-Link Deco M5 mesh router network in my home.
research that I’ve done everything tells me to make sure the other two network notes for the network are totally disabled, powered off (and they have been.) so now my mobile phone and the HomePod are definitely 100% on the same node and network.
Then after researching further, the community is saying QOS is a culprit and that if you disable QS on your network devices that you will be able to authenticate through to the end of the set up.
Unfortunately, not every network device by every vendor allows you to disable QOS, like mine.
And finally due to cost, I have had to downgrade my network download and upload speeds. Now the utilities in my network app do speed test and record the speed tests. I’m concerned, though that Apple develops products in a super super clean environment where the products always work 100%. That’s not reality though and that is where most of us customers get into trouble because we’re not wealthy like they are.
I don’t know what I’m gonna do about these HomePods that don’t work.